Loot is a wonderful thing. In Destiny, items drop in the form of white, glowing polygons called Engrams which you can pick up and immediately equip. However, the colored (green and blue) Engrams are encrypted and you'll need to bring them to the Cryptarch NPC at the tower to "decode" the item before you can use them. There are also items you can earn from gaining faction experience, doing crucible matches, and participating in other activities which I'll mention later.
Yes, picking up loot from enemies and chests is a blast, but do you want to get the best equipment possible? You're going to have to change your questing a bit. First, look for the golden chests hidden in each zone. These contain high level items and sometimes unique rewards like mounts. Also, you can redo Strike missions on higher difficulties. The enemies will be higher level, but they'll also drop better gear.