One of the first if not THE first question you should be asking yourself is: What is my exit strategy?
If I buy/lease/control this property, how will I get paid?
The days of Carleton Sheets/Bob Allen/Get into the property at any cost, any way because it will cash flow every month and appreciate at 5%+ a year are LONG GONE.
This means that you need to do more due dilligence BEFORE signing up a deal. A motivated seller is a required BUT NOT SUFFICIENT condition.
If the house is a FSBO and the owner is 100K under water, your (and the seller's) options are VERY limited no matter how motivated the seller is.
Another thing that the new market means is that subject to is much less viable. I do not recommend taking negative equity properties subject to. There may be markets that did not appreciate so strongly in the past where subject to make sense but in a lot of markets, subject to is just bad.
Really, there are not a lot of exit strategies: lease or sell. (Lease option is a hybrid of both). Leasing is more of a medium to long term strategy. Selling can be any time frame.
Then for selling, you decide on FSBO, listing it with a realtor, owner financing, or maybe lease option.
That is the basic decision making process.
Plug in the numbers and go...