Elo is about how good of a player you are not how many games you have under your belt. I, along with my friends, who all sit between 500-950 wins ish a piece will que 5 up and frequently beat teams with 1500+ wins all over there team.
Also, you have to consider what roles you're playing and who you are playing. In ranked, you first need 5 champions that can do each role effectively.
After you have 5 champions, work on getting 10. Once you have 10, its a good idea to learn hard counters to strong champions like LeBlanc, Talon etc.
Once you know a few counters, I'd work on getting 3 champions for each role.
Personally, though I feel if you play anymore than 30 champions you will lose luster with some of the others you do not play often. Always play champions you've played recently in ranked, so you aren't off just the hair that the person you are playing with isn't.