especially at your early 20's

First, get a job and save money to invest. Put money into a savings account for the time being.
While you accumulate more cash, invest your time learning about investing, through books and seminars etc. It's worth it trust me.
Read every book you can find until you are confident. And I mean REALLY confident because, obviously, investing involves risk. risk of losing money.
Then once you're comfortable, open an online stock brokerage account (Etrade, scottrade, tradeking, etc etc.) if your comfortable with stocks. Or plan to buy an investment property if you're confident about real estate investing. Or bonds. or whatever.

Hard part is saving your money. Being young and early 20's makes it hard to save, you want to party and do stuff with friends. Just save as much you can, don't eat out so much or not taking that one trip could save another $1k. Just depends on you and how motivated you are.

Source(s):
I started investing at 23. I graduated with a degree in engineering at 21. I wanted to know more about money and why investing was so "important" so I took the time to find out. I'm 25 now. I'm doing pretty good :D I want to retire early, that's what motivates me. *beep* working. hah.