Find a scuba place and go there to buy. Ignore any bullshit the guy tries to feed you about the goggles and their quality. Pretty much the only concern is how they fit your face. Many are different sizes as some people have ugly shaped faces. Do not get a type with a Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) water exit nose, scuba/snorkel people will think you are a Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!).
The actual snorkel part is pretty basic. They have a type that prevents water from going down the tube. If you are afraid you may suck at it, you could spend the extra money for this. I didn't tho as it is mostly a waste of money.