Hi Loulou,
I do not usually wear goggles but a pair which are double glazed can help prevent misting,also a pair with an amber lens will help with glare and give better contrast in flat light.If the dealer is any good (someone who skis or boards themselves and not someone helping out at the weekends who does not do snowsports)they should be able to advise you and make sure you have te pair best for you.
Oakley along with Bolle,Cebe,Vuarnet etc all use top quality lenses in all thier glasses and goggles so most will be good,also the lens needs to be both UVA & UVB protected,but again most are as amatter of course.
Ho this helps, and enjoy yourself in the mountains,
jon.