You’re a private pilot, and no doubt sometime soon a friend or business acquaintance will ask you to fly them somewhere, and they’ll sweeten the offer with cash or some other form of compensation.
Can you do it? The answer to the question is “no.” However, let’s say your friend wanted to go to Boston for a meeting, but you were already planning to go for a sightseeing trip that same weekend. In this case, you are allowed to split fuel, oil, airport, and aircraft rental fees. That business flight could also happen, assuming you are attending the same meeting, and the flight is incidental to the business. If there’s any question, decline any flight involving money. The FAA is very strict with these rules. Break them and you’ll lose your certificate.