Best lighting to shoot in is normally in the morning hours or sunset before the sun is too harsh and overhead. Cloudy or hazy days also make for great lighting. When I shoot indoors, I like to use a cool, cheap lighting set up.
Create a naturalistic looking setup on a piece of cardboard or something like that, then find 1 or 2 desk lamps. Set one up at an angle from behind the snake and raised about 2-3 feet from ground level. Now take 3 white garbage bags and put them between the light source and the snake. This diffuses the light tremendously. Take your other lamp and set it up at about a 45 degree angle in front of the snake (the side you're shooting from) use 1-2 white trash bags this time. This is your main light source so you want it to be stronger.
You have a camera that will let you shoot manual, so shoot automatic ISO, aperature at about f/8, and shutter at about 1/125 to 1/150 of a sec. This should give you pretty good results with a good depth of field to make a sharp image and should be fast enough to take out any movement.
Now, when you're focusing, remember that when you push the shutter down half way it locks your focus point. You can recompose the image with the button held down half way, then push the shutter down the rest of the way to actually take the photo. So, when you're focusing, focus on the snake's eye and then recompose the image as you want it to look before hitting the shutter.
Hope that quick run through helps. I can do more when I'm not typing on my iPhone lol
PR