The easiest way to check if your mask fits is to hold it over your face and inhale through your nose. If the mask is a good fit, it should stick to your face without the strap around your head. If you can still inhale, then the mask does not fit properly.
When you're diving, the air in the closed spaces inside your ears is compressed which gives you a "squeezing" feeling. It is necessary to prevent ear damage to "equalise" the pressure. We've compiled some tips to help you do this, including a video.
Ear Equalisation Video Demonstration
How to properley equalise your ears
Step 1: Descend until your head is just below the surface.
Step 2: Pinch your nose and firmly but gently breath into it
Step 3: Make sure you control your descent and continue to equalise as you go down
Step 4: If you're still having trouble clearing your ears, try tipping your head to either side as you do this.
Ear Equalisation Tips
Tip 1: If you are experiencing pain in your ears, ascend slowly until the pain is gone and try equalising again.
Tip 2: Never go diving when you are congested or have a cold - even with medicine, if you become congested again underwater you'll get reverse block on the way back up
Tip 3: Equalise early and equalise often! Once you have got the technique down, you should not be experiencing any pain whatsoever!
Tip 4: If you are still having trouble equalising, try the alternate methods of moving your jaw or swallowing.
Tip 5: Take it slowly, a lot of people have trouble equalising after not diving for a while!