I wait until something comes up (or looks like it might.) For example, I don't care for anal. A little fingering or tonguing is OK, but I don't want a dick in there.
And yes, I have tried it, and I've tried it more than once. I don't think I have to like anal any more than I have to like raw oysters, crawdads, or carrots. Anal just isn't my thing. I do think that I have other things to offer. If my guy seemed to be trying to work his dick into my bunghole, I'd tell him then.
I also don't like facials. A guy can cum in my pussy, between or on my tits, in my mouth and I'll swallow, whatever. But I don't do facials. And guess what? Most guys couldn't care less. Unless they watch a lot of porn and have become conditioned to the idea that that is the way it's supposed to be done.
I would much rather have that talk about what I LIKE, rather than about what I don't like or won't do.
Lindy