I need insulating layers and general use pants for hunting and other things this fall/winter.

I'd like to find this stuff as cheap as possible as I'm losing weight and won't fit into this stuff next season.

I'll be doing a lot of hiking but also a lot of sitting in 20-30f temps.

For base layers I'm just going to find some cheap merino.

For pants I was thinking midweight nylon ones.

I don't know what type of insulating pant I'd need or how to layer pants.

A decent jacket with some insulation and material that won't rip easily because of branches and stuff would be great too.

Any recommendations for specific items, advice on layering, or just general advice would be much appreciated.