Get the answer in writing. A thorough annual often finds ADs NOT
complied with even though supposed to be. A recent teardown of my
engine revealed the wrong size valves used at the last overhaul.

Set at least 10% of the purchase price aside to cover surprises.

Best approach is a complete review of the logbooks from day 1, but that
means you need to go look after you get serious.

The Twin Comanche has a tricky fuel system - lost an acquaintance a
number of years ago trying to switch tanks while flying an instrument
approach.