there are many 30+, more than a few 40+, and even some 50+ providers out there, it all depends on where you are located, and where you do your looking. (My top four experiences of 2005, all involved ladies ladies 34 and older.) Of course, there are also plenty of mature, beautiful ladies in their late 20's out there. If you can't find your first choice, be flexible.
As for your age, appearance, hair color, wrinkles, etc, don't worry, these really don't matter. Assuming that you are dealing with an experienced, well-reviewed lady, she knows, and understands, that is her role to fulfill your fantasy, not hers.
Arrive on time, arrive clean, or ask to take a shower, and treat her with respect. Once you do this, you will have her attention, and who knows, your personality might even lead to a real connection with her, I know I have a few times over the years.
Okay, I realize the purpose of the hobby is having sex, not making connections, but I found that having sex with a provider who is a friend is a real bonus.