Any advice for getting lethargic winter trout to bite?

I'm fishing around Idaho and Montana (I travel a lot) and like to hit rivers. I've normally done this in the summer and fall, but I'll be around some good rivers in southwest Montana in the coming weeks and wanted to give it a shot. What would you recommend for getting trout to bite during these colder winter temps? I'm a spin fisherman mainly, but also do some fly fishing as well. Thanks!