I'm having a bit of trouble with Destiny. I'm currently level 20 and I'm no longer getting experience. Also, I'm looking for some members to play co-op with. Add me: Hugo_AFC
You will need to start getting any armor parts that contain 'Light'. This is now your experience if I recall correctly.
You don't just get one helmet with +2 light and automatically hit level 21. you're going to need to get as much as light as possible. example 15 light from a rare blue piece of equipment. you can do strikes or patrol missions to gain reputation and vangaurd marks. you then can use marks to buy legendary gear such as weapons, chest armor, gaunlets etc.. Legendary armor starts off with about 20 light. I advice to buy atleast 1 helmet from xur this weekend if you have enough strange coins. If you buy 1 legendary gear with your marks you should automatically jump up a level or 2.