Something small and manageable to start with, IMO - at that age, you've probably not been hit with so many financial responsibilities, so avoid committing to a plan where constant new investment is required (such as a minimum investment savings plan).
There are a couple of different approaches you could take, but considering your suggested circumstances and lack of experience in investments, some kind of small investment plan you can change the amounts in may work, such as some form of sharebuilder program.
That's merely my first thought for your circumstances - of course, you could make the effort to really research the markets and then employ a serious technical strategy.
