I would rate it similar to backgammon. (That is, I consider myself good but not an expert, and would expect to win ~45% of games against an expert, and maybe 80% against a beginner.) Disclaimer: I have played semiseriously over the net and at local competitions, not major regional tournaments or for high stakes.
A starting point is browsing around the "tips" portion of the American Cribbage Congress's website and Michael Schell's
www.cribbageforum.com site . The latter includes - or included a couple years ago, anyway - a fair bit of detail on how an allegedly expert-level computer program HALSCRIB was created. (You can buy the program, but I haven't... I confess, I have a secret project of writing one good enough to beat myself.)
If you prefer reading books of tips / practice situations with analyses, there are several by Dan Barlow in print.
Given my somewhat unusual geographic circumstances, I can't really answer questions about typical stakes in the "real world."