Keep the violin in clean condition is a good habit.
Always have two soft, clean cotton cloths (about handkerchief size, in different colors). One is for cleaning off the rosin dust on the violin, and the other one is for cleaning the fingerboard. You can either find these cloths in your household, or you can buy cleaning cloths specifically for violin in violin shops.
Wash your hands before handling the violin. Sweaty hands make the fingerboard very sticky, and it is a good idea to keep the fingerboard and strings clean.