Adam I agree with you about the fit,.... However I disagree about there being constant pressure. If there is increasing pressure on the mask, then you have mask squeeze, which can be aleviated by exhaling through the nose into the mask. Chris, as Adam pointed out, there is a difference between goggles & a mask. The biggest difference between the 2 is that a mask has a nose pocket for equalization of the mask & an area to get the thumb & fingers around the nose for equalization of the ears (this will be covered in your class) & goggles do not.
The most important thing about your equipment, whether mask, fins, snorkel (OK, not as important on this one)& boots is FIT followed very closely by comfort. I can not stress this enough.
Mask- should fit & seal across the face. One of the better tests is to put the mask on without the strap, pull a very slight suction (& I mean very slight suction). Let go of the mask & it should remain in place as long as the suction remains, if it falls off, then there is an air leak. If air can get in, then so can water. A leaky mask can ruin a dive very quickly & cause a diver a good deal of stress. Depending on your face size & shape will largely determine what kind of mask will fit & work for you. Be aware that facial hair (especially a Mustachio) can also affect how a mask seals. As for styles, you can go with 1 lens or multiple glass panes, clear or black skirts,..... The only thing I personally steer students away from in masks are the purge valves. 1. you will be taught proper clearing methods, so not really neccesary. & 2. the purge valves tend to get junk caught in them & then start leaking. Its just another potential failure point in my book.
Snorkel- a very basic piece of equipment. the biggest things about a snorkel is that it be long enough & have a flexible bore to allow for comfort during use & allow it to hang out of the way when not in use. From there you can decide if you want a regular snorkel or a dry snorkel (has a valve that cuts off the barrel should water come over the top of it).
Boots- Used with adjustable foot fins. They should fit like a pair of tight, but comfortable socks. It should not bind or pinch the toes or foot in any way. Also the foot should not move around freely in them. Keep in mind that they will loosen up a little (not much, but a little) once they are wet. You can go with the full length boots or the sneaker style. Although most are pretty close, different manufacturers can size a bit differently.
Fins- Full foot fins (shoe- like pocket built in)- These should fit snuggly like a pair of shoes, but not bind or pinch the feet or toes in any way. It should fit tight enough to prevent the foot from sliding around, causing chafing. These fins are great for warm water (no boots needed) & soft/ smooth surfaces.
Adjustable foot fins- Boots must be worn with these to prevent the strap from chafing. These have ajustable heel straps for a better fit. Once again you want it to be sufficently snug when the straps are pulled. You do not want any binding or pinching & you do not want the fin to be "floppy' on your foot,... once again the chafing thing. From there you will want to choose a fin that fits your leg type. Too stiff a fin & you may have problems with leg cramps, then again, if not stout enough, you may not get the power you want. These fins are better suited for more temperate (cooler) waters & rough terrain.
To recap: #1 is fit, #2 is comfort, #3 is function for your type of diving & #4 is style (if that is an important feature for you). Your LDS should be able to help you find good fitting equipment.
It's usually a DM's pet peeve for a student to call his/her mask, goggles. Go to your Local Dive Shop (LDS) and try on a lot of masks. Don't look at the prices. What are you looking for is a good fit on your face. Also, I would press on the section of the mask that is right above your eyes in the center. If you feel this pressure, I would say try a different one. Imagine that the pressure is going to increase at depth. This pressure on your face almost right between your eyes will maintain constant. 
