Since the canyons are on Navajo lands, you must hire a Navajo guide--we were very happy with our young guide, Kyle--with Antelope Canyon Navajo Tours. Searching for Antelope Canyon photo tours on Google will result in a number of results that can be cross-referenced on Google, so I won't make any specific recommendations. Be certain to book a PHOTO TOUR, and not a regular tour. Photo tours are longer, the regular tours are shorter and are not geared to photography.
I had a bit of trouble booking a month in advance, so do not leave this to the last minute. Getting there is explained on most of the guide websites, but be careful, because your GPS will want to lead you past the guide center ( a dusty lot, with a small shack, and a number of blue and white pick up trucks with beds converted to sit more people). If you see that lot within a mile or less of the three large coal-fired smoke stacks, you're in the right spot (not too far from an intersection with a gas station and rest area).
You are driven in the back of a modified pick up for about 20 minutes in talcum powder red sand, to the entrance of the cave. Your guide will give you a few quick pointers--things move very fast, follow the tour guide, and shoot when he says shoot--before entering the canyon.
It is, in fact, like combat photography. You are in a narrow environment, with scores of other photographers and tourists jostling for position. You may worry that you'll only get 30 seconds to shoot an iconic view, but don't worry. The guides will move you quickly from venue to venue, but they also bring you back for second opportunities. The only issue is that the light is very ephemeral, and the famous light shafts move into obscurity quickly. If you follow your guide and communicate with him or her, you will get the shot you want, as there are light shafts throughout. There's even a shot in my collection below, where you can see one large and one very small light shaft striking the sand. Keep your eyes open, don't rush. Our guide was very determined to get us the shots we wanted, he seemed very concerned that we were happy with the service, a fine young man who did a great job (please tip at the end; they work hard for their shifts). I saw some people getting so wrapped up in trying to get a shaft-of-light shot that they were missing other gems, and anyways, there are more than one light shaft to be seen in the tour. The guides will toss sand in the air to make the light shaft more visible.
Anyways, my only advice would be:
1. Arrive early. They won't hold a tour because you decided to take a leisurely drive into town to get a latte. If you're not there, they leave. Don't be late and infringe on other photographers' precious time in the canyons.
2. Dress for hot weather and lots of dust and sand. PICK a lens to shoot with; lens changes in the canyon are very dodgy, because you stand to get sand in your sensor. I chose a Canon 16-35mm for general use. As you exit the back end of the tour halfway through, I used the cleaner outdoors to change to a Zeiss 20mm for a different effect.
3. Low light means using a tripod. I just kept my tripod on my camera the whole time. I use a Really Right Stuff tripod and head, so I can carry my Canon 5Diii and lens on the tripod with confidence that it won't fall off. But, be cautious that you don't ding your camera against a camera wall as you move from spot to spot.
4. A tripod means a shutter release. You've traveled this far, so use best practices and do it right.
5. Minimal kit. Bring water to drink and cleaning kit in your backpack, but too much kit in the canyon is crazy. There's barely room to move past one another in places. I lost my black Fisher Space pen in the sands, and it was clipped to my photog vest......
6. I did not use any sort of polarizer; just use a plain lens with a lens hood to protect it from knocks in the narrow canyon environs. Keep your camera close to your body, and protect it like you would your newborn. The canyon walls are not forgiving.
7. Be polite, but speak and touch . When I was setting my tripod into a position and someone's foot was nearby, I'd gently touch their shoulder and say, "My tripod is right behind your foot, thank you!" Courtesy and communication will go a long way in the tight confines of the canyon.
Be prepared to move hard for 45 minutes, shooting and moving like an infantryman in close quarters battle. Once you come out the other end, take a quick breather, change lenses if you want to, drink, and get ready to go back in. BRING A BLOWER BULB for cleaning. Blow off any lens before using fluid and cleaning cloth lest you grind the silica into the lens and scratch it. Also, a good blower is critical for blowing out the inside of your camera on lens changes to keep out dust. Always point the camera downwards so that any dust blown out doesn't fall back in the camera body. Be sure you know how to do lens changes with confidence and dexterity before you try changing lenses in Antelope Canyon. And don't change a lens inside the canyon if there are gobs of people kicking up sand. Only do so--if you must--when there are no other people in the area kicking up dust that can enter your camera and possibly dusty up your sensor and pooch the rest of your vacation.
Concentrate, know what you want to shoot, listen to your guide and hustle hard. You can drink and rest later.