Nonnahob shared this with me earlier (hope it wasn't posted yet):
Loot Chests Do Not Level With You
You'll definitely want to get chests your first time through an area, since chests don't level up with you - if you come back for them once you're above the general level of the patrol zone, you'll wind up with gear you don't want.
Engrams, However, Do
If you get an encrypted engram, it actually does level with you - it's locked to whatever rarity it was when you discovered it, but it won't be assigned stats until you have the cryptarch in town decode it. So, if you're about to level up, wait to have the cryptarch decode it until you're sure you're ready for an upgrade of whatever weapon or armor type it is.
Dismantle The Gear You Don't Want
Happily, you don't have to go to a shop to sell extra gear in Destiny - you can dismantle it directly from your inventory and get cash in return. Do so often, particularly with common weapons that you've long since outgrown.
Consider The Robot
There is a sad, lonely robot in the hallway between the town plaza and the lady who sells ships. He stands there all day and night, tirelessly sweeping the same spot on the ground. When you pass him, pause to consider the robot. See how he ceaselessly repeats the same activity over and over, how unaware he is of his own insignificance? Perhaps we're more like the robot than we'd care to admit.
Remember That You Can't Pause
You can't pause in Destiny. Ever. Don't forget that! Otherwise you'll proooobably get killed in an embarrassing way next time you get up for a pee.
Master The Boost-Jump
The boost-jump is one of Destiny's most mechanically interesting tricks - after you get a few levels, depending on your class, you'll get an ability that lets you make special jumps. Each character has a specific sort of move, and they all take a bit of getting used to. For example, as a Warlock, if you tap the jump button twice quickly, you'll get the maximum boost - don't wait until the pinnacle of your jump to press it, or you won't get much juice. However, there are times, particularly in competitive multiplayer, where you won't want to ride a full boost, since it'll leave you vulnerable up in the air.
Eventually you'll level up enough to unlock the ability to control what direction you float in, too, or upgrade its speed. It's worth taking some time in a safe area to practice and get a feel for getting around.
Play A Dangerous Drinking Game
Every time Peter Dinklage reads a line in a way that indicates he has no idea what the words he's speaking are supposed to mean, take a drink. Warning: Only play this game if you've had something to eat first.
You Don't Always Have To Be A Hero
On missions, you'll occasionally enter an area where there are no respawns. That means that if your whole team goes down at the same time with no one to revive them, you'll have to start back at a checkpoint. Sometimes, your teammates will get aced out in the open, and you'll have to risk your neck to revive them. Remember, however, that they also have a countdown respawn timer. If you're safe behind cover, it can be smarter to wait for your teammates to respawn on their own, rather than risking dying to revive them, since if you die, you'll all have to start over. You'll feel guilty leaving them out there, but it's okay - you have your team's best interests at heart.
Keep Up With Bounties
Bounties are basically challenge-based quests—sometimes with specific orders to carry out or just a specific enemy to kill—that offer substantial XP boosts and can really help boost your level.
You can only hold a certain number of bounties at a time, so you'll want to prioritize. Are you planning on spending the next few hours in the Crucible for rounds of competitive multiplayer? Then you'll want to take all the Crucible-specific bounties so you can (hopefully) knock them out in one or two gos. If you're planning on spending a lot of time on the Moon, it makes sense to carry only the Moon-based bounties so you don't have to do too many return trips. Also, remember that the bounty robot refreshes its stock every so often, so check back whenever you're in town.
Get A Bounty For Patrol Missions
You can usually get a bounty that gives you an XP reward for completing six of the "patrol" sidequests on each planet, so it's a good idea to wait to do too many of those until you have a bounty that'll give you extra rewards for completing them.
Remember To Check In With Your Vanguard
Each class has a specific Vanguard character that they can check in with between story missions. That person is usually waiting for you to turn in trophies after completing major quests, and it's a very good idea to check in with them on the reg. Not only will they give you a reward of a good piece of armor, you can also buy some really powerful gear from them for cheap, provided you meet the level requirement. It's also smart to look at the loot you can't afford to use yet, and make a mental note to come back once you've reached the appropriate level.
Give The Crucible A Go, With Bounties
Some players will likely skip Destiny's player-vs.-player Crucible multiplayer entirely, preferring to focus on the co-op grind of the campaign stuff. (Of course, other players will probably focus only on the Crucible.) If you're one of the former type, push yourself to give the Crucible a shot. You can earn some hefty XP rewards in the early goings by taking bounties to complete a certain number of matches—which, crucially, you don't have to win, just complete. As it just so happens (clever Bungie), that number of matches is right around what it takes to get yourself familiar with Crucible multiplayer, and likely get interested in playing more.
Pay Attention To The Waypoint On Your Mini-Map
This might sound silly, but it's actually pretty easy to forget to check the waypoint in the upper-left corner of the screen and spend a while cruising in the wrong direction. Destiny's waypoint-checking system is a bit annoying, since you have to take out your Ghost to get the markers to appear on the screen, but once you get a certain rhythm down, you can check pretty easily.
Un-Check Waypoints Before Hopping Off Your Sparrow
When you're on your Sparrow speeder bike, it's easy to hit the button to make your mission waypoints pop up. However, if you just hit the button once, you'll have your ghost out (instead of a weapon) if you hop off your bike shortly afterward. Which is annoying. Get in the habit of pressing the waypoint button twice, which will "put away" your ghost (and waypoints) so you're ready to rock in case you need to quickly dismount.
Be A Brawler
Your melee attack is one of your most useful weapons, and careful tactical use can help you dominate the battlefield. Enemies will usually stick to one piece of cover, so if you can clear a path up and around that piece of cover, then melee the enemy who was hiding there, and you'll have headed off one of the flanks of the battlefield, killed a hiding enemy, and wound up safely behind cover. Provided you've spent points building your character in this way, you'll also be granted some kind of bonus for each melee kill.
Aim For The Head
A slightly obvious tip, but: If you're taking on a bunch of the Fallen or the Hive, remember to aim for the head. You can one-hit-kill a number of enemies that'd take a few body shots to go down. That can be particularly useful when dealing with the Hive's running melee attackers, since you really don't want to let more than one get within swatting distance.
Go In One Level Up
Especially if you're playing solo, Destiny becomes a lot more fun if you're just sliiightly higher level than the enemies you're fighting. If there's a level 10 story mission, hit it at level 10 or level 11. If you go in at level 8 or 9, it'll be much more of a slog. That said, if you're really good at the game, or have a few high-level friends, going in too early is a good way to give yourself a stiffer challenge.
Leave One In The Chamber
Remember to reload your weapons, particularly your special and heavy weapons, in between encounters. Nothing's worse than whipping out your rocket launcher to hit a massive boss, only to find yourself hiding behind a rock because you forgot to reload the last time you used it.
Use Secondary Weapons Or Lose 'Em
It's tempting to be stingy with your grenades and secondary weapon ammo, but it's actually best to use both liberally. You'll find secondary ammo lying around all over the place, so it's pretty easy to use your shotgun/sniper rifle/whathaveyou more often than you might think. Obviously, save your grenades for groups of enemies; it's rarely worth it to waste a grenade on a single enemy, unless it's a big raid boss. You may also want to consider saving grenades for crowd control when things get too chaotic for comfort.
Ration Your Super Attacks
Once you've played a few hours, you'll have a good collection of abilities at your disposal. You'll have your primary weapon, your secondary weapon, your special weapon, your grenade, your melee power-attack, and your super attack. Learn to inventory each of those separately, which will give you a sense of what you've got "loaded" at any given moment.
You'll want to ration your special attacks so that you aren't wasting overpowered weaponry on lower-level enemies. Almost every encounter builds to a crescendo with a boss or a mob of powered-up regular enemies, so keep that in mind. If your super is charged midway through a wave-defense challenge, save it for the boss that's likely just around the corner.
Don't Pick Gear Just Based On Basic Stats
It seems like an easy calculation: This pair of gauntlets has 80 defense and this other one has 110, so...obviously the higher number, right? Destiny's weapons and armor that are categorized by either a blue or green icon are upgradeable. So if you're a fan of Auto Rifles and if that 80-defense gauntlet has an upgradeable perk that works specifically for Auto Rifles, it actually might be more useful to you to build on the setup you want. Before the upgrades are made available to you, you can view them by clicking for details on each item. It's a good way to plan ahead and think a bit deeper about how you want to customize your loadout.
Keep Two Different Secondary Weapons On Hand
Your primary weapon will be something like an Auto Rifle or Hand Cannon or Scout Rifle or Pulse Rifle. The secondary weapons are a bit more diverse, like energy weapons, sniper rifles, and shotguns. It's important to keep both a sniper rifle and a shotgun on hand for both the campaign and the Crucible.
At any point of time, you can swap between items in your inventory. When you're trying to pick off enemies from a distance, you can rely on your sniper rifle. But at the end of that raid, when you're likely in a more enclosed area stuck with a raid boss of some variation, the shotgun becomes incredibly useful. Same goes for multiplayer matches, which will occasionally call for different tactics based on which map you're on.