I'm in the final stages of bug fixing my own tools and CSS for my EPUB content. In my version control repository, I have 160 revisions of those tools and CSS. The first 159 revisions almost all produced EPUB files that were 100% compliant with the specs but still looked like dingo crap on at least a few popular readers.
Unless you limit yourself to very basic markup, complying with the spec is only the first 1% of the work. The other 99% is making it actually look good everywhere.
The way you get EPUB projects is to post samples of your work. My advice would be to take a public domain work, format it, and post it somewhere so that people who are looking for those sorts of services can download it and evaluate your work.