I just ran across this great article in the Wall Street Journal Six Mistakes Housing Investors Make

A quick synopsis:

Mistake 1: Confusing a cheap deal for a good deal.

Mistake 2: Overlooking key costs.

Mistake 3: Forgetting that time is money.

Mistake 4: Assuming you will sit back and watch the rent roll in.

Mistake 5: Underestimating repair costs.

Mistake 6: Assuming that owning a rental is the same as owning a home.