Mutual funds + dollar cost averaging = good money in the long term without worrying about it (or even thinking about it, for that matter). I use AIM investments (formerly Invesco).

I do $300/m regardless of price, so when prices are low, I get more shares, when prices are high, I buy fewer. I've read the mathematical defense for this and it fawking blew my mind.

:edit: IRA's work on a similar principal, but they've got tax advantages too. Opeining an IRA is never a bad idea.