Nice to be able to plan ahead.
Consider structure as well, such as tightening joist spacing below the tank, telepost placement etc.
Do think about non standard dimensions such as a deep front to back, as
untamed or the classic but extreme
Oregonreef.
I'll as give the standard advice, READ LOTS, but do search out build threads. Posts like
Lando's and others you can get quite a bit from pictures. Even if not planning a CL, take a look at
OM's picture forum as lots of layouts.
Also try to see some tanks first hand. Being able to talk about a system while standing in front of it can really be helpful.