I was 26 when we bought our first home, this was a HUD home we lived in and fixed up and turned into our first lease property. It has long since been sold and reinvested. Never to early too start.
Pick up a copy of rich dad, poor dad by Robert kyosaki. Lots of good info.
I wouldn't start with anything you can't pay for if it goes unrented a month or two.
The stock market is no place for the uninitiated.
Cashflow is king! Having money coming in very regular is way better than a lump sum once. Trying to protect your lump sum is much more difficult than getting paid every month. And that which is paying is insured against loss. Tax advantages are rediculous, so get you a good CPA to make sure you are maximizing.