Triclopyr n diesel is what I do. If you close to a nice oak, you can just duble gridle and use straight diesel. I also have the green tordon rtu when near trees I want to not kill. More use that lightly with grape vines on trees I want to save. More mature trees than not grow back from cut stumps. The young growth is great for winter forage if the specieis is right. If you don't want it to grow back cover the outside layer of the stump with diesel, green tordon, or triclopyr mix.
General, general rule of thumb, smooth thinner bark species can be killed by applying some of that triclopyr n diesel. Hack n squirt good trick is to get a rounded axe face, chop a little pocket tat can hold your chemical.
Chainsaw girdle, just 2 complete circles within lets say 2 or 3 inches from each other.
Also, spring is a bad time to do this. Sap flows. Some trees have flows during warm spells in the winter when you want to go outside.
If lower stuff looks very well browsed, higne cutting isn't a bad idea at all. Depending on the species. ONly downside is it can make a mess to clean up a few years later. Not a bad thing to do near entrances of seclusion zones. I do it lightly at my hunting lease. They are easy going, but the main prupose of that land is logging. So I don't overdo some things over there.