It will quickly become apparent that hair fetishism is a broad category, and people differ a lot in their likes and dislikes with respect to hair. I will tell you some things I do and don't look for, speaking purely for myself.

Wet hair doesn't do much for me. Most sites include it, and I don't mind that, but it isn't something I seek out myself.

I don't really look for porn in the sense of other people engaging in sex acts. I don't find it offensive, but it doesn't really turn me on either. You probably will expand your market if you do X-rated stuff, but you shouldn't feel that you have to. If you haven't already, check out Marianne Ernst's amazinghair.de for an example of what can be done with no nudity or explicit sexuality at all.

I like "peekaboo". I like it when your hair falls in your eyes, and you struggle or pretend to struggle with it. If your hair is so you can't use both hands and both eyes at the same time, that's a good indication.

I like watching updos come undone -- not just the clearly deliberate bun drops you will frequently see, but hair coming undone accidentally or "accidentally on purpose" as you move around. I like it if it gets in your face in the process. I like it if you try or pretend to try to keep it from coming undone, but it does anyway.

I like it when you struggle with loose long hair as it gets in your way while you try to do something. Chinalonghair.com has some delightful videos of Feng Ye playing soccer and climbing stairs that exemplify this. Vnlonghair.com has some where the model plays with a hoop or a basketball.

If you want to add to the erotic effect using the rest of your body, I like clothing that teases: short, tight skirts that ride up; tops that your nipples slip out of; shoulder straps that keep slipping off. For some examples, go to dailymotion.com, set the age gate off, and search "downblouse" and "upskirt".

If I were a video producer, I'd make some where a model struggles with her skirt, her top, and her hair all at once, perhaps while trying to clean, exercise, dance, or just walk -- but she only has two hands and her clothing and hair gang up and get the better of her.

Again, this is just my two cents worth. Other people's likes will differ.

Remember that what you are doing is art, not just business. It's art that not only is created entirely or partly by you, but also depicts you. That gives you a double right to control the work. Pay attention to the customer, but make sure to do what you like, and like what you do. Not only is it your right, but it will improve the quality of what you produce. When you enjoy your work, it shows.