Another piece of advice is, don't ever forget that you're actually working for the patrons, your audience, not some megaplex chain or manager who doesn't know better. The patrons pay your salary, so keep them happy.
As for reading, Film-Tech is a good place to be! I've discovered that there's always something new to learn around here, and the people here are both knowledgeable and helpful.
My best advice is "Always make sure you thread in frame." Nothing looks less professional that starting the show out-of-frame. It's so easy to do it right, so there's really no excuse for doing it wrong!
Go back to 03-20-2000 and look for the topic title: "Books / Training on Projection" which John Pytlak started. It has several good suggestions. In fact, just go through the last year of posting- you sure to find a comment about the equipment you actually use, or a situation you've been in.
There really are not many books about projection; it's just been one of those things that has been passed from one person to another by "hands-on." If the head projectionist (or equivlent) who is showing you stuff is good, you will learn a lot. If not, you are screwed.
It usually doesn't take any longer to do something correctly (than incorrectly.) So if whoever is training keeps showing you "short-cuts," be wary.
Also, there is a wealth of information from Kodak under "Film Notes" if you follow the "manuals" link below. I highly recommend finding out the brand and model numbers of everything in your booth and downloading the manuals as well. Even if you only learn the correct name for the parts, you'll be far better off. 
And of course, if you've got any questions, just ask. You'll be amazed at how fast these guys can solve a problem right here. It's team effort at it's best.
You can get on the "snail mail" subscription list for "Film Notes for Reel People" (now called "Cinema Notes") by e-mailing pamela.jackson@kodak.com.
The Kodak ScreenCheck Experience has a projectionist training program: http://www.kodak.com/go/screencheck
Kodak's publication H-23 "The Book of Film Care" has lots of good information on film handling, cleaning, and storage. It is also available on-line at: http://www.kodak.com/US/en/motion/support/technical/care.shtml
Of course, you can always download Joe's video, and learn more than you ever wanted to know about projection! 
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Work your ass off, learn as much as you can don't be afraid to take on a "s***" job once in a while. (Up to a point!)
Working in the "Movie Biz" is highly political. There will always be somebody that'll knock you for personal reasons. No matter WHAT people think of you personally, they won't be able to assail your work. As much as people back-stab each other in showbiz, there is one thing that can override politics... the ability to get the job done.
If you make yourself known as "the guy who gets things done", you'll be able to rise above almost anything.
Yeah, I know I sound pretty jaded but it's from MY OWN personal experience. I've had so much sunshine blown up my ass I think I've got colon cancer!
The main reason I've been around this long is that people sometimes depend on me to do things that others can't.