Just a pair of clear protective glasses are the best bet. You can't see them too much. Nothing is period really, so these are the best bet. Make sure they're up to the correct safety rating though, there are details on another thread about this somewhere!
Just glasses for me. Today a sniper got me plum in the cheek with an 8mil K98, and that hurt a bloody bit, but I'm undeterred.
just glasses for me too, unless i'm doing CQB like at wotan, and even then it was just a scrim over my face and neck to guard against point blank hits in the dark.
I got pinged twice, right on the end of the nose yesterday, so i look like bloody rudolph the reindeer now. 
Still, i find full masks spoil the period look too much, so it's worth the occasional face hit.
Glasses alone . I know some people use gumshields as well which always struck me as a good idea to protect your teeth, but one I'm too lazy to get round ot organising. 
I prefer to use bolle silium glasses, but I usually find I get fogged up quickly in almost any glasses.
In the end I usually end up switching to the low profile mesh goggles I have.
ha ha, yep I have mesh glasses (dont steam up,,,,EVER!) and I know what its like, that 8mm sniper hit me on my left cheek low enough to feel it on my side teeth! but, i diddnt blubber! he he
me and my mate use masks. thats me and my mate standing up in the pic below
i personally will never where glass's and refuse to. but for a photo sake i will but not for gaming.
It cost me about the same when my tooth was shot out.
right thats it-bought a gum shield and never got round to moulding it-will now!!!! Just use guarder glasses and scrim scarf.....
Bolle glasses (as recommended by Yith) plus a shemagh and keeping the gob shut for outdoors fun.
A FF mask for CQB although I'm ordering a neoprene face mask so I can use my glasses.
Bolle glasses (as recommended by Yith)
At your own risk!!!
If something goes wrong, sue Bolle, not me! 
I said what I use... I didn't "recommend" them... that's a completely different thing!