It is entirely true -- a mask HAS to fit. Field of vision, available colors, and everything else come second to fit, because a mask that leaks is a constant annoyance and causes diver stress. If you are lucky, an inexpensive mask will work for you, but pay what you have to for one that really fits. The best way to check fit is to place the mask on your face, hold your breath, and push on the mask with your fingers and then release. If the mask will stay put, it fits well. If it falls off immediately, it does not fit. (Inhaling doesn't work as well, because if you create enough suction, most masks will stay put.)
I also prefer the inexpensive snorkels, especially for students. The ones with the fancy dry valves are seriously top-heavy and tend to fall over, twisting the mask strap and making the mask leak.
Buy an inexpensive set of paddle fins, something like the Deep See Pulses. See if you can find a set that come with some kind of elastic, bungie or spring strap (a lot do these days). You may decide to get something else in time, but don't let anybody talk you into $200 fins to begin with, and please, do yourself a favor, and don't start your class with split fins. You may choose to use them later, but make your life easy at the beginning with paddles -- they make stabilizing yourself in the water SO much easier.
I will disagree with the folks who say not to buy a wetsuit -- if you have very little body fat, you will get cold, even in the pool. I wish more of our students had suits, because I hate throwing them out of the pool for shivering!
