Ive always just sort of done it lol i think about out lets inlets/ hiding equipment and also making territories for your fish, seen as you have a tall tank i think a centre piece is a good idea maybe a large bog wood leaning off the back wall going down to the centre.
Post a pic
for example a couple of pot hides you can just cut with an angle grinder a small bogwood witch my parrot has dug under and the anarcis jungle hides my heater.
I think its my lighting i have a blue tube and a pink tube, blue is for marine but i like it in that tank. Thats been my most sucessful plant and most practical it breaks up any fights as the fish end up confused in it lol im just going to keep growing and splitting it.
If its a tall tank, I think centering things into an artfully arranged pile would look nice. Use driftwood propped up on rocks to create height. Tall plants like the elodea placed behind the pile will compliment it. would love to see pictures of your tank so we can see what you have to work with.