My credit score is in the mid 500's and i don't have any income. how can i be a real estate investor?

Save up some money for a down payment on a home and fix your credit score..

When you're trying to rebuild your credit score it's important to get a comprehensive view of what is actually effecting it...

Your Credit Score is calculated with the following breakdown:
35 - Payment History
30 - Credit to Debt Ratio
15 - Credit History
10 - New Credit
10 - Credit Types in Use

If you excel in one area and lack in another, only fixing the areas which you lack are going to improve your score.

I've got a lot of information on my blog about credit scores, and I get a lot of questions so feel free to check out any of my posts on millionster.com; I believe my articles here address many of your concerns but if they don't and you still have any specific questions feel free to leave a comment and I'll reply.

How Can I Increase My Credit Score
http://millionster.com/articles/debt/ask...

and

10-Ways to Boost Your MyFico Score
http://millionster.com/articles/debt/inc...

Also be sure to check out the promotional links I've listed here to help you get a better picture of your creditworthiness:

MyFico's Full Credit Report
http://millionster.com/go/myfico

Suze Orman's Credit Report Repair Kit
http://millionster.com/go/suzekit

30-day Trial of Credit Score Tracker with Free MyFico Score
http://millionster.com/go/fico30

without a downpayment, you are SOL these days. Play the lottery.

Check out books at the library and learn everything you can about investing. One suggestion is Start Small, Profit Big in Real Estate by Jay P. DeCima. You have the desire, now get the knowledge, without which you won't succeed. The money will come later. Go for it. I believe in you.

by improving your credit score and getting a job!

If you have nothing to invest how can you be an investor?
Figure out how to earn some money.

Shhhhheeeeesse!

Get a job.