Bounties, bounties, and more bounties. You need those to level up your light on your weapons and armor. When ever you turn a bounty in, make sure you have weapons and armor equiped that have not been leveled up yet. Preferable legendary gear. Purple.

EDIT

and whatever you do, do NOT discard the Strangers Rifle. Ever since the pulse rifle buff, that thing has become very powerful for a level 16 weapon.

As Guru said, do bounties. That's going to be the quickest way to get to level 20. Once you're at level 20, a few things are going to unlock and the way you level is going to change a bit. The game doesn't really start until you are a 20, and then will kick into another gear once you're leveled up enough to raid.

Finally Level 20! now for more levels!

Now that you are level 20, you need to do the daily as often as you can. You also need to be doing a public event every day that you get on. Until you are capable enough to raid, those are going to be your sources of ascendant materials which you will need to rank up.

i did a few strikes with 2 others. then i got some light on my gear and it said i may now level up to 21. lol

Well tonight was my first time as Sword bearer for Crotas end. Never did get him down but at least I came close a couple times. Man that is frustrating to be the one everyone is counting on and to come up short each time.

Level 22 now. took a day and a half off for family stuffs, but im back! lol

Yeah, this game can take over your all your free time if you are not careful. LMAO

3 heavy weapon legendary engrams this week........

ALL OF THEM BECAME SHARDS, OR ENERGIES.

So, what's the deal with upgrading your exotics with Xur? I've read that if you've already upgraded them on your own, it will reset the progress.

Does the defense/attack/intellect/etc. of your guns/armor suffer if you just do the latter? For example, my Achlyophage Symbiote I maxed out on my own has the right amount of light (36), defense (441), but only 93 in the stat boost.

When is it good to start doing PVP? i dont want to go in there and get completely owned because my gear sucks lol. Im level 24 now btw.

You're good. PvP (other than the Iron Banner) evens out level differences.

Ignore the "updates" if the exotics were received after Dark Below expansion came out. Some of these weapons were lower rated prior to the update so they put this in for people to get them updated to their current power. Really stupid to because they reset all progress when you do. the fact they don't even tell what the upgrades are for is really confusing. I wasted Strange Coins on that just to find out they didn't upgrade anything.

I would say ignore the exotic weapons if the one you have caps out at 331. The exotic armor could possibly have a better roll on Intellect, Discipline or Strength than your current piece. It is up to you if you want to spend the time/resources on upgrading. If it's only a slight different in stats then I won't bother.

I would have to disagree with that. 331 on one weapon is not the same as 331 on another. right now pulse rifles and scout rifles bury auto rifles when maxed.