In the Army we found the kids from the Deep South would dress much too heavily when exercising. They would sweat, then get cold: they did not have the experience base to realize you can sweat in below freezing temps. Bundle up to sit on a tractor, bundle down if you start working. You want to be a little cool, not overheated. That's why layers are great. I usually wear a down vest under a wind proof jacket, so my arms are free but my body core is insulated, and you can unzip one or both.
Alcohol may give you a flush of warmth but opens blood vessels in your extremities and you may lose heat faster, so not a good idea while working for an extended period.
Coffee is a diuretic (makes you pee). Cold weather also reduces your thirst reflex so it's surprisingly easy to get dehydrated in cold weather. This makes you cold and dumb. Drinking cold liquids can also chill your core, just as warm liquids warm you up.
Your body tries to fuel your brain no matter what, so wearing a hat is important. It's not the 40% number folks used to throw around, but it's significant: you lose a lot of heat from exposed skin, wherever it is. My favorite winter hat is a Carhartt insulated ball cap with ear flaps.
If you are wearing heavy gloves and have to take them off, first unzip your jacket and put them inside so you don't lose them and they are warm when you put them back on. I wear thin running gloves that fit tight and allow you to use tools, with heavier gloves or mittens over. "Trigger mittens" are much warmer than gloves and give you some dexterity.