I know that I can be a very prickly person to deal with. I hold myself to very exacting standards and I have a hard time not judging other people by those same standards. But I'm working on it.
On the other hand [or maybe in an effort to balance my critical self] I try very hard to observe and comment on the good things people do, or to compliment others. If someone I've hired does an excellent job, I don't just pay them, I thank them, and very specifically mention the things that they did that I appreciated. Like workmen who clean up after themselves, instead of leaving a mess behind them. I talk to the supermarket checkers and baggers, ask them about their day, thank them for getting me bagged and paid so efficiently. I utter words of empathy to the person behind the counter, if the person just before me was especially rude or uncooperative. Sometimes putting a smile on someone else's face makes the whole day worthwhile.