As far as tips go, I'd never go as far as to hold a grudge towards someone for not tipping me for my work. However, I must admit that I am more inclined to book clients that have tipped in the past, if only because if they did, I take it as a sign they had as great of a time as I.
Gifts are also appreciated, but I think it's a case by case thing. Do a bit of research, see if the lady has something about gifts on her website... Look for hints! ;)