Most gear, even when maxed out will not be able to get you to max level of 32. The only gear that will get you to level 32 is the gear you get from do the Crota Raid. Then if you max level them all and have 1 fully leveled exotic piece of gear you will hit level 32. It's much easier to get to level 31 though.
To get to 31 you only need 1 fully leveled exotic and the rest of your gear can be bought from the Vanguard or Crucible quartermaster. I recommend using an exotic Helm for your warlock because helms are more expensive to buy from the quartermaster than the other 3 pieces of gear.
The way I leveled my Warlock:
Got an exotic helm and leveled it up.
Bought Gauntlets, Boots, and Chest from Vanguard Quartermaster in the tower.
Leveled those up.
Now I am level 31.
A good way to get vanguard marks every day is to find Daily Public Events. You will get 4 marks every time you complete one and you can find them by using the website: DestinyPublicEvents.com. You can do them more than once per day. I know you can do it at least 3 times a day to get vanguard marks but you may be able to do them more than that. I can't remember if they stop after 3 times.
To get to Level 32:
Play Crota raid as much as you can to get the raid gear now that you are level 31.
One last thing:
The level cap will be raised from 32 to 34 with all new gear coming out in the newest expansion. The release date for the House of Wolves expansion is May 19th. The good news is that they will have a way to upgrade ANY legendary or exotic gear to be able to get you to level 34 when maxed out. So rest assured that the gear you are working towards now to get to level 31 or 32 will still be useful with the next expansion. Unlike how the last expansion made all our old gear practically worthless!