Aside from using a Light Desktop Environment (not Gnome and I would shy away even from KDE Plasma or Cinnamon as they are mid-range) and installing TLP, there are limits to reason as to how to reduce battery drain.
You have performance expectations along with a desire to get the most length of time of battery. And they can contradict eachother.
For example, you set certain apps to not run at all to conserve battery, unless they are called or launched.
However, since they are not running (at very low power levels) in the background, it takes more power and time to load and launch the app; causing you to actually shorten your on-battery time.
You might have some luck using preload (sudo apt install preload), but it also may cause more drain other times.
Really, the best thing you can do is get an idea of your average battery time, then adjust your behaviors and actions to try to influence it. This allows you better fine tune control over what affects your battery.
And... accept the limits that Battery Time imposes.