I think you were asking about buying one unit ( a condo) in a 2-unit property, not buying a whole two family to live in one unit and rent out the other. So there are a few things to consider about living in two-family.
First, you will have no control over the other occupants. (You won't in a single family either, but there is usually more separation.) You will have to think about how you will get along, because decisions about when to fix the roof, paint the siding, or replace the driveway (for example) will have to be agreed on. If you buy a condo in a multi-family, make sure you read the condo documents carefully and understand how these decisions are made. If there are condo fees, who controls the spending? I once had a client who had trouble selling her unit because exterior repairs were needed, and the other owner refused to contribute. In another sale, my buyer rejected a beautiful unit because the unit next door had trash all over their side of the yard.
So if you are thinking of a two-family, your best bet is to buy the whole thing, and rent out ther other half. Then the advice below from Marybeth wiill be very important. Good luck!... more