Dealing with shitty people well is a skill most of us do not have.

First impressions are super important. You can practice over and over with each person. Try to increase your external self awareness. The way you initially present yourself is key. Everyone is a fraud and liar under the surface. It is only a matter of what layer. By providing a service for money, you infer a certain caste that promotes abusive prejudice due to the servile nature of the exchange. If you try, with self awareness you will likely find ways to alter the rules and level the playing field or even take control over them.

You need a few sharp responses to silence fools. Like, "I do fantastic work in Photoshop with just a few hours of premium labor." That will murder 99% of the fuckwits.