I'm the same way. I've posted art shops on different forums before- not knowing what I was doing. I struggle with my style as well, it's like a mix between 3 different styles and it's very difficult for me to draw in a specific style I have done in the past. However, since this is the case you can simply just show a few examples and state how your style may not be the same as the references, but similar. I'm sure people will keep that in mind while ordering from you.
You can start off drawing whatever you feel comfortable with, and be sure to state what you CAN and CAN'T draw- most people will and should respect that. Just keep in mind- it's your hard work! You can simply decline the commissions you feel unable to do. Also, never under-price your artwork as that could discourage you and make the shop feel like a chore in the process. You could also look at other people's art shops and get an idea of prices, etc.. Just do whatever you feel if comfortable for you, but also follow the forum rules and you should be good!
Correct me if I'm wrong in some way, anyone. I'm always available for some enlightenment, too.