duo's
If you dont know the client, the joke "oops forgot he was here" (said near the beginning) or a variation there of; is not funny.
If you're still fully in your lingerie (or whatever) and the other two people are naked and fully engaged, there's a problem. If something is mentioned, dont make it seem like its an annoyance for you to catch up.
general
Dirty talk isn't necessary, however small talk during sex is a big "wtf?!"
I do like friendly teasing (not the sexual kind, the joke kind) with someone I'm familiar with, and I will just do something with someone I'm familiar with. However someone new I'm meeting for the first time I'm going to be quite polite with, be on my best behavior, and be asking "is it alright if I do x..." until we start to get any sort of rhythm or the feeling out process is done (pardon the pun) - maybe you should act the same and not just go into teasing someone right away (seriously would you rather have someone ask "I'd really like to go down on you do you mind" or would you rather someone just flip you over, start on you doggie and unannounced stuff their thumb up your butt?). A goof is my natural state of being, but lets get there first by having some polite interaction first when we meet.
Inline with that last one (and the 2nd from duo's), if physical activities are actually getting going, and the client removes some of his cloths but doesn't go after yours, he probably doesn't really want to have to strip you. I understand chemisty, ymmv and such; but it's a client/provider dynamic, the power/authority is on the provider's side and the experience is supposed to be tailored for the client.
As a general tip I could give provider's (I'd say I'm sure most know it, but since I've heard during conversation "we aren't mind readers", I'm guessing alot dont). People tend to do to others what they want done to themselves. Not necessarily in the act itself but how it's done. Example: I'll go down, take my time getting there, tease around for a fair bit, start slow, keep my hands moving as much as possible, and go from there; why? Because that's kind of how I want to be blown.