Even after what has been said against self-teaching, I'll tell you that I have been doing studying bagua for over a year and a half with some success. How much success? I don't know, but at least I am learning. I sought out bagua because I wanted to learn
it, not the martial art that's taught at the local McDojo.
Now as for a sparring partner, that's a must. You need to be able to practice this stuff on a real person, so I would spend some time looking for someone to hit and keep you working hard. With this application and even stumbling around through videos and good books, you'll begin to learn those fundamentals and core principles through trial and error at least. And who knows? Maybe you'll connect with a teacher here and there that can help!
Good luck!
Ben Schmuhl
http://www.PaKuaChangJournal.com