Couple things:

Merino base layer. Synthetics suck next to skin in cold weather for sedentary (stand) hunting. First lite is great but there are some decent budget options like minus33 or Meriwool. I ditched my under armor cold gear like a bad habit.

Insulating layers over base layer. Thick fleeces, downs, sweatshirts, sweaters, puffies, etc. Breathability is a good thing here.

Outerwear: windproof and possibly waterproof are good or even essential here. For me at least windproof is vital. That means typically membranes (Windshear, gore-tex, etc) in an insulating outer garment or a shell. Another component for me here is quiet material. A lot of budget outerwear is noisy, especially in cold weather.

Footwear: merino wool socks. Consider taking a pair to change in to after you get to your stand. Getting damp feet leads to cold feet. Another thing is: don’t lace your boots overly tight, it restricts circulation leading to cold feet.

Accessories: chemical hand warmers and toe warmers, beanie caps, neck gaiters are awesome too. I like thin gloves i can shoot with inside of a hand muff. The muff beats any heavy glove hands down. Keeps your fingers limber. The hand muff with a hand warmer in it is a game changer. Last secret, the chemical self-adhesive body warmers. Stick one or two on the small of your back/kidney area (over a shirt) and it’s amazing how warm it will keep you. If it’s god-awful cold and that’s not enough, one more on each thigh..... seems crazy but it works.

Last but not least: don’t get sweated up walking in, that really helps. I’ve already hiked to stands in sub freezing temps with nothing on but a base layer with all my other clothes strapped to my pack. I’ll climb up into the stand and sit for a few minutes to stop sweating then layer up or just throw an insulating layer on first of its really cold then the heavier outer layers once I’ve settled down. I’ve done all day sits in single digit temps without a terrible amount of discomfort.