The Community of Disc Golfers and About All Things Disc Golf
Use a spotter. Take turns fulfilling that role. Have them run or walk up the fairway. They can unbury discs and set them up on edge for easy location. Then everyone else advances while the spotter goes back to throw and they spot for him. Don't be lazy or you WILL lose at least one disc out of your group if the ground is already trampled.
Obviously pay attention to everyone's throws more closely.
No white discs. Neon yellow isn't really good either I've learned. Dark discs are easier to find in winter. I actually break the no white rule with a wizard that I throw off the tee. I never have any issues finding the shorter throws.
Don't do the ribbon thing. I ripped mine off after two throws. Spotters are the ONLY way to insure no lost discs.
I played an Ice Bowl last Saturday where the snow was roughly 8-12 inches deep. I put 2 feet of lightweight red ribbon on each disc with clear packing tape - applied when the disc was warm and dry. I checked with the TD before the round to get permission to use the ribbon. I had only one disc where the ribbon pulled off - and that was in my bag. It was a very technical course played entirely within the trees - no long, open shots - and I noticed no real effect on the flight of the disc (The ribbon hung down from the precise center of the disc, the edge of the tape right in the center of the small plastic dot you can find on almost all discs). Other people spent huge amounts of time searching for discs - groups backed up on the tee three and four deep. I never had trouble finding my discs and my playing partners swore they were getting ribbon the next time they played in snow.
Don't let people talk you out of it - try it for yourself. If you don't like it you can simply pull the tape loose and continue playing.
if you use ribbon, use Electrical tape to apply it when the discs are warm. It should hold the entire round unless you accidently pull it off. I have actually used the same ribbons for multiple snow rounds with electrical tape.