For long ops, like 2 days or so, I have made hides before at centralized locations where people could not really see me. I was not using a sniper at that point in time so it was pretty unnecessary, but it helped me stay concealed so I could pick people off at random. Best idea I've seen is a cheap leafy net draped over a branch. As long as it blends well and you are in a darker area, near a pine tree or whatnot, no one will notice you on a sunny day.