Great fun with both sexes.

Ladies first: It's been my experience that every woman masturbates a bit different. If you can get one to do it with you (many won't admit they even do it - must be the sex fairy that left the toys in her drawer), pay close attention. The way she masturbates is the same way she gets the most pleasure from oral sex! Duplicate with your tongue what she does with her finger and she's yours for life.
With men: It's a joke of the "I wish I had a dollar for every time . . ." sort of joke. Every man I've met in the last 45 years that told me he only wanted to jack off together, ended up cumming in my mouth. They may sincerely believe that's all we were going to do, but an offer to use my mouth when he's close is always accepted.