From my experience i belive coyotes dont persay distinguish color but movement. you say its really cold so i expect there si snow. white decoys will be less effective. I have used many decoys, and ones that contrast against the background color work the best. i know deer can see the color of blue jeans becasuse of the UV reflection. Perhaps blue would work for coyotes. you should try to use different motion with colrs to see which works best with motion. you will need to call in the coyotes so i suggest you purchase or borrow if able a call. Primos makes great calls for reasonable prices. the HotDog (red and black witha long chamber) is a great way to use the coyote vocalizations to call them in since their breeding season is right now in my area or soon elsewhere. for another call, the DoubleWhammy by primos is great becasue it gives you great rabbit/miouse sounds and coyote sounds as well. calling them will not be easy as you seem like you havent done this before much.put keep at it and i ensure you will get some results.