Beautiful map! For a first attempt, this is extremely impressive. I really love your style and can't wait to see an update with it populated!
The only suggestion I can make is to maybe try darkening the background a bit, so that it contrasts with the lighter cavern interior.
EDIT: By populated, I mean with elements related to the types of creatures your players will encounter. For example, some spider webs throughout, or just in the main section where they hang out.