Choose a bunch of masks and try them on in this manner:
Strap folded forward over the lens, place the mask on your face and inhale through your nose. DO NOT put the strap over your head.
The mask should collapse toward your face. DON'T EXHALE THRU your nose.
Shake your head side to side; if it stays in place, nod vigorously. If it still stays in place, you have a keeper mask. If the mask doesn't collapse to your face, move to the next one, regardless of how it looks or "feels".
DON'T over-tighten the strap! Sealing on a mask is done by the skirt and facial fit, NOT by tension of the mask strap. The silicone grease trick is an attempt to mold your face to the skirt and rarely works for clean-shaven faces.
When you find a good sealing mask, adjust the strap so it just keeps the mask in place and tweak the fit after using it a few times.
Something else- go to Wal-mart or a similar store and check out their masks. A lot of times, you can find a mask their that fits really well and is dirt cheap. Just make sure the lens of the mask is marked 'tempered' before you commit to buying one. I haven't bought a mask or snorkel in a dive shop in 35 years.