What base layers have you been using?
What works for me is a lightweight merino blend - I use the Stone Glacier Chinook - that wicks well and dries relatively quickly. Same idea with socks (I use midweight Smartwool). The whole idea for me is to keep moisture off my skin as much as possible. Something that is lightweight enough that it takes me a little bit to get warmed up, that wicks well, and that dries quickly. I go with tops and bottoms here, specifically for the wicking.
Somewhere around 40, I'll wear my mid layer which is either a Peloton 240 hoodie or a Sitka Heavyweight hoodie. Both have their place - the Sitka breathes better so if I'm wearing the mid that's what I go with. If I'm packing the mid, I'll take the 240 hoodie.
Once I'm stopped, on goes the mid and then the puffy. I like the Kuiu Kenai a lot. If it's cold enough, I'll pack the Kenai pants too. I try to avoid wearing a shell unless I have to because of noise. I'll pack a Warbonnet Stash jacket for a cold wind or passing showers. If I'm looking at sustained rain, I'm going with the Outdoor Research Foray.
The little thing matter too - beanies, neck gaiters, gloves, socks. I like to have a dry pair of socks and a dry beanie (Peloton 97) in my pack to put on when I stop. I can skip the neck gaiter if I have the Sitka hoodie. I like a light merino glove like the First Lite Talus with a fingerless wool glove on top (currently using Fish Monkey Wooly gloves here). I can't find a truly warm pair of gloves that I'm happy with, so I use these and my pockets.
Somewhere around or just below freezing, I stuff the mid layer in my pack and wear in a Sitka Stratus jacket over my base layer. Once stopped, off with the Stratus, on goes the mid, then an Outdoor Vitals Loftek puffy, then the Stratus goes back on along with the Kenai pants. I can stay pretty warm like this for a long time, but the key is staying dry on the way there.