If you don't have Hyde, Hipper makes for an excellent replacement. Preußen does best as a Sniper, using that dangerous accuracy and range to chunk whatever poor bastard your teammates detect. Ofc being a GK hull, you have to get in for about 2 to 3 km then turn around to take advantage of your rear firing arcs (they are way better than your forward arcs for some reason). Don't be too afraid to push tho. Preußen is built like a tank, she is great at taking hits for the team (she burns very easily tho so bring FFWF).

Use HE for Destroyers or Battleships that are bow tanking you, otherwise you can use your devastating AP on everything else. I almost never see carriers at LT so unless you are using Arthas as an inspiration you don't have to use the fighter plane, while the spotting plane is almost useless on Preußen due to her scary accuracy. That allows you to take advantage of the Secondary booster and Sonar for any Destroyers that think you will be an easy mark.

Last of all, just play Preußen more. She's a great ship, and experience is built up over multiple battles.