I'm no expert at tuning either. I just started racing last season with my first nitro engines...and I struggled ALL season long only to find out I was fighting a losing battle since I bought used engines. I read everything I could find online....talk to guys at the track while they were tuning and I picked up little tid bits here and there. Now....I do pretty well with tuning. I have had a few new guys come to my place for some tuning help, and low and behold....I managed to get their engines running pretty well without even breaking a sweat.
So just practice practice practice and read read read. Then put what you've learned into action...and it will all "click" once you get a few right.
A good way to practice tuning (for me at least) is to just give your needles some random turns before you get out there....and when you do...tune the engine again. You will get really good...really fast ;-) Just don't lean it out too much with your random tunes so you don't damage anything. You always want to start with a rich tune when possible. So if you get too far out of whack....richen it and start over.