I try and make any email clear and concise. I give a brief overview of myself, my experience, scene interests (often in point form) and how they align with the activities she will have listed on her website. I list my limits and make it clear that I understand hers. I'm also sure to include the duration I am interested in booking and a specific date /time of day (if that applies)

I've found showing you have read and understood any booking instructions can go a long way towards establishing a working relationship.

I am polite and respectful but not servile as I am not interested in booking any pro that maintains an over the top dominant attitude outside of session time.

Just my 2 cents but it has worked well for me over the years.