It is indeed tough when you're starting out. If you're not careful, account minimums and fees will eat up your earnings!
That said, how much you save is more important than how much you earn on your investments.
For now, I would invest into broad market funds (Total US fund, Intl index, etc), until you reach enough to get into more specific geographic/industry/mkt cap funds.
My sister just started her first job last year and had this "problem", so I just advised her to put all IRA money into a Target retirement 2055 fund. As her balance reaches $6k, I'll break off a piece and put it into another area (i.e. Intl index fund, REIT, etc) and within 1-2 years, she'll have enough different funds to start investing in all of them.
It takes time, so don't feel the need to rush. Even a mountain is made up of a bunch of tiny rocks.