2. It is up to you. You need to figure out for yourself what your strengths & weaknesses are, and what your short-, medium-, and long-term goals are.
3. Stay away from rent-controlled areas.
4. A good deal on a 2-unit building is better than a bad deal on a 4-unit building.
5. Look for upside. If the rents are maxed out given the neighborhood, then there’s no upside.
6. You probably won’t be meeting with the seller face-to-face, but if you are, I’d find out his motivation(s).