First and foremost the model should agree upon having an escort or assistant with the photographer before you plan the shoot. This article assumes you have done that.
1. The escort should know what they will be doing during the shoot. They should not simply be sitting or standing and staring at the shoot. This will make the photographer and possibly the model very uncomfortable. The escort needs to bring something quiet and out of the way to do unless they have been asked to help with the shoot.
2. The escort should not be talking during the shoot. Again, this is usually very distracting. This includes talking on the phone or playing games on their phone with the sound on.
3. The escort should not be the model’s jealous boyfriend or anyone else who may take issue with the shoot. The last thing anybody needs is a jealous boyfriend complaining because a pose is too sexy or too revealing. Discuss limits beforehand with those involved in the shoot. Limits should be between the model and photographer. If the model has some agreement with her significant other then she should consider that, but there is no reason to discuss this with anyone else.
4. The photographer has the right to cancel the shoot if the escort is being a problem. There is no reason the photographer should put up with any sort of poor behavior from an escort, particularly if the escort is making them uncomfortable or like they might physically harm them. Better safe than sorry. And models should realize that photographers will likely see it this way just as a model might choose not to shoot with a photographer who comes off as “creepy.”
5. The escort should not be taking photos during the shoot with a camera, camera phone, or otherwise. The only exception to this would be if everyone agreed they wanted behind the scenes shots, but that would be a very rare exception and not something I would push for.
Assistants should follow the same general rules. They are there to help out when needed and should stay out of the way otherwise. For example, some assistants might be there to help with wardrobe or posing. They might be there as a lookout, to help models up and down from higher places, to help arrange props or whatnot, etc.
I say this often and I think this is a good place to say it again: put yourself in the other person’s shoes. If you were the photographer and there was an escort on your shoot, how would you like that escort to behave?
Another issue I have heard of involving escorts (and assistants) a couple times is at group shoots. I feel it is particularly important to let the host of the group shoot know you will be bringing someone extra and to clear it with them. Many times space at these events is limited and it is better for the event to have as many models as possible versus having fewer models with escorts. It is also very important that your escort does not cause a problem because if you have issues at a group event just imagine how many bad references that could create. I would also recommend that your escort or assistant stays close to you (unless the event rules state differently) to avoid complaints that they are wandering or staring at other shoots.
Remember anyone associated with you can affect your reputation and the references people give on you. It may not seem fair at times, but that is how things generally work.