Most of the time as soon as you pay for a sexual service they only see you as a client, and might go on dates with you but only as a sugar daddy.. To increase your chances when you meet an attendant you'd like to date DO NOT get sexual services. Just take the massage, but you should still TIP well. Ask about them in the room, stuff like hobbies, ambitions, fav music and movies. These girls are there to make money and not intentionally looking for love, so their guard is usually up. DO NOT offer to help them out of the industry, they hear that crap all the time and then assume you just want them all for yourself. DO NOT belittle their choices of working as an MPA..
When they offer sexual services politely turn them down saying I need to know someone before I can have sex with them, I just came out of curiosity and stayed only to meet you. This helps if you aren't ROCK HARD.. lol
If they stick around to chat with you as you are getting dressed to leave at this point you can tell if it's a good time to give them your number with an "I really enjoyed our conversation, would love to chat more.. Here's my number, no pressure to reach out as I'm sure you get people giving you their number all the time.."
Planting all those little seeds of not being a client, a good conversation, thoughtful, and down to earth.. This will in my experience and opinion increase your chances of having her reach out to you. At that point, it's all up to you.. ;-)