First: post-security you will find some of the most disgusting food ever served in an airport, but hey it’s also expensive and the servers don’t hide how much they hate being there! However, there is a little shop near the left-side stairs that sells better alcohol as well as soft drinks, and various food including (last I checked) pretty decent sandwiches. Just get provisions there and have a seat near your gate.
Second: when the security lines are moving too slowly it’s often worth trying the faraway one, which is actually outside the main hall. It’s so insanely counterintuitive, it’s the last one to get backed up.
Third: on arrival you may want a train, and it’s not at all obvious what one goes where nor even which ticket you need. You can use a standard subway ticket with any train departing from the airport, and you can buy that ticket in advance with the BVG app. Oh, and the S-Bahn is probably not the train you want if you’re reading this comment. Just go to Hauptbahnhof and reorient from there, IMO.
Guten Flug!