I have a copy of Access VBA Programming , Charles E. Brown & Ron Petrusha, that sits on the corner of my desk. You can also gain a lot but looking at samples, like my multi search sample, which by the way was not my original work but something I pulled apart and made "Improvements" to.
If you set your self little challenges, that step just outside what you currently know, and use Google and the resources within this forum, you will find that bit by bit your knowledge and skills will increase.