I was recently chatting with a manicurist and she remarked how hand models are related to each other by only their hands. They come from all walks of life and vary in appearance. A lot of the other hand models I have met were actresses, models, musicians, students, etc. There is such a range of personalities!
So it really doesn't matter what you do or really what you look like - if you have great hands (or any other great parts) you should consider parts modeling.
The first thing to do is to try and take the highest quality pictures you can of your hands. I would then recommend you send these pictures to local manicurists and beauty photographers to see if you can arrange a test shoot or collaboration with them. This will give you professional looking pictures that you can show to an agent.
Check with your local modeling agencies to see if they have a parts devision or can refer you to the nearest parts agencies.
It is kind of unusual to be "discovered" as a hand model but if people often compliment your hands or they just tend to photograph well, it might worth pursuing.