This is a good question.
I’m sure it’s different for everyone, the experience of choosing a seller.
I read the description, and like a long, complete, thorough, easy to understand one. I look at the graphics and see if they look as though some thought was put into them, and if they look mature and professional.
I look at the profile, and like ones that show the seller is proud of their work.
I read reviews, at least ten of the recent ones, and also check the negative reviews to see if there is a pattern that shows the seller has had problems in the past. All sellers are going to have some bad reviews, but it’s the general pattern I look for, to see if it’s a recurring issue with the seller.
I look at portfolios also with a critical eye.
I have friends who buy things on fiverr, and have noticed that they go by much more of an impulse decision based on things like the graphics alone. I’m a thorough decision maker. They are sudden impulse buyers. So each person is different.