Hi, Alison-
        Yes, your years of experience should affect the rates you charge, both
for the amount of time it takes you to complete a job, and for the level
of skill you bring to it.  Just take a look at a piece you did several
years ago, that you were very proud of.  You are probably still very
proud of it, but you also know that you can do better now that you know
more.  I gradually raised my rates over the years (25), as I felt my
experience and skill allowed.  It was all pretty arbitrary, and I've
relied (and continue to rely) on the Guild, and now this listserve, for
approximate levels.
        What your market will bear also is a factor:  I live in a small town
(Battle Creek), but it has a few "world-class" companies (Kellogg's,
Upjohn in Kalamazoo, General Foods), so it's a bit of a toss-up. Not
everyone has small-town expectations, but many have small-town expense
accounts.
        Just don't undersell you talent. Even beginner-level artists are
usually far better than anyone hiring them; that's why they're not doing
the job themselves!

-Gail