Aquascape for my 55gal

Ok so I’m finally getting ready to start my aquascape in my tank, either this weekend or next depending on my work, any suggestions or do’s and dont’s. I’ve read about taping your tank off into 9 sections like a tic-tac-toe board and where the lines cross that should be a focal point. Is this a good rule of thumb to go by? I know it’s whatever you want but also don’t want to have to rip it down for long while.

I’ve searched google for different aquascapes and have seen so many there all running together. I’ll have 80+ lbs of dry rock to play with. Most I’m sure will need to be broke down some as there’s only I believe 10 piece. Mostly huge chunks.

Oh and do you use anything to hold the rocks together? I’ve seen this putty stuff at the lfs and read super glue gel works good also but you know how things you read on the internet are.

Does the dry rocks go directly on the glass bottom correct? Then do your sand around it? Or cover the bottom with sand then dry rock on top?

Thanks in advance everyone
Matt