Awesome replies everyone. I really appreciate your input.
The thing I find interesting, is there are a few things (in this thread and other places) that I've seen multiple people write exactly the same, and then I've seen things that are exactly opposite for two people. For instance, some gents LOVE when I let them undress me and take their time with it, and others are disappointed and a little put-out if I don't jump out of my clothes right away.
This hobby is so incredibly varied, which is both wonderful and frustrating, lol. I'd have to add open communication to my list of desired qualities. I find that the clients that are very open with me about what they like and want are usually the ones that leave most satisfied, and I feel most satisfied by a job well done.
And also I would have to add patience and compassion to my list. The ones that forgive my little mistakes, my awkward moments, my quirkiness. The ones that really understand that I'm a person, and a relatively young one at that. I don't have it all figured out yet, and the ones that are patient and compassionate are the ones I LOVE to see, again and again.
Sometimes I think we forget that everyone has ATFs (even providers), but we can't all expect to be everyone's ATF. I really believe that ACTING like an ATF is the best way to become one. Ladies, pay attention and remember what he likes. Make him feel welcome and comfortable. If you want him to come back, give him a reason to. Gents, do something that makes you stand out to her, in a positive way. If you want to be treated like her ATF, then act like it. Bring her little gifts that let her know that you KNOW her, and what she likes. Be considerate and understanding. Talk to her like she's a PERSON. Be a tipper (it doesn't even need to be a lot. Even just an extra $20 can be the highlight of my day, because it makes me feel like he really enjoys me and feels like I am valuable, and recognizes that I don't just try to give the minimum acceptable effort). All of these things are some of the ways my ATFs got their status.
So, shout out to my ATFs. You know who you are, and you know that I just adore you and appreciate you! You are the masters of my hobby universe, and the reason I love my job. <3