1. Pay them whatever they ask you to pay - they are always fair.
2. Make sure you let the person in the front know IN ADVANCE that you are looking for a handjob. Say "handjob" so everything is clear.
3. Make sure you get a picture of the handjob girl - it's a good way you'll remember them and will come back.
4. They generally prefer to be paid in a variety of currencies and coins.
5. Read the other reviews on here - they'll give a you a good idea of the protocols and what to expect.