Being on both sides of the mentoring table, it's definitely an important topic which is hardly covered. One thing I like doing is in case I do use one or more of the tips given by the mentor, email him/her and tell them how it worked out, even if it's a couple of months later. I think that this is the reason entrepreneurs become mentors and most of them are very interested of hearing if their tips were useful. Sometimes I also share things which didn't work for me and why, I find out that mentors want to hear about these experiences as well.