There are really only two types of real estate investments - short term (cash) or long term (income/appreciation).

Short Term (Cash):
Types: Wholesaling, short sales, flips, rehabs, etc...
Return on your investment:
Time Investment:
Experience:
Money/Credit Requirement:
Objective:
Benefits:
Cons:

Long Term (income/appreciation):
Types: Buy and Holds (a.k.a. Rentals), Condos, Retail Office, Duplexes, Self Storage,etc...
Return on your investment:
Time Invested:
Experience:
Money/Credit Requirement:
Objective:
Benefits:
Cons:
Summary:

Current Market: Tons of sellers, lots of buyers, currently a buyers market. Unless you can find a really good short term deal, I would suggest the long term appreciation investment and wait for the market to turn, then flip for a profit. Overall, both styles offer great return, but what you need to decide is if you are wanting the big check right now, or if are you okay with building passive income now, to collect the big check later.