Anal giving means that the escort is willing to give anal sex to the punter, either with their penis or through the use of a strap on. This gives the recipient the chance to experience what it is like to be penetrated, which can leave them feeling fantastic and also fulfil a desire that many people have but don't act out. You can both start with some light anal play first before moving on to full penetration, as the control should be with the person taking it.
One of the most important things to remember about anal play and anal sex is that there is no rush. Some mistakenly think it is better to get straight in there so that they can get the pain over with, but it is better (and safer) to take your time. Working your way up will mean that, not only that the client would be more relaxed, which will allow for better access, but they are much more likely to enjoy it and want to try it again. Using plenty of lubrication can also help, as the escort can slip inside a little easier.
Anyone who is looking to be the recipient of anal play should remember to clean thoroughly. Simply standing in the shower and allowing the water to pass over you isn't enough - you will need to actively get the nasty surprises out of there. Using warm water and soap, lather yourself up all over to get yourself nice and relaxed before you go to your ass. Very carefully clean the general area before focusing on your asshole. Slip a wet finger slowly in there, gently rubbing to remove any of the stuff that has accumulated there. Give yourself a thorough clean and you are good to go.
When it comes down to it, you should both communicate what you want. If the punter would like some rimming before they take their surprise, they should let the escort know so that they can be fully relaxed and enjoying themselves before it happens. If either of you need to take a break throughout the proceedings, tell the other person. It will ensure you both have a great time while also respecting boundaries.