Against the cold :
The most important thing is to avoid the wind (especially hands and feet).
There are good hand guards available for 40 €,
but even the do-it-yourself-budget-solution helps.
For the feet, use simple rain covers (with a sole).
For traction, use at least knobbies (for instance TKC 80).
Heidenau K60 Scout are M&S tires (Mud&Snow)
and work very well on Snow.
There are also snow chains for motorbikes,
but they aren’t easy to mount.
I used “snow claws” instead, 5 for 125 €
For the body, use a Winter Overall such as Thermoboy
LC8 