Plan, Plan, and Plan some more. I know it is tough to sit and look at an empty tank, but if you have the time, make sure you are 100% comfortable with your plans. I took a long time to get my tank up and running and am very pleased with the results thus far. Think about things like location, stand height, water changes, electrical load, ATO and water storage......I would also suggest that you buy the best equipment you can afford. In my opinion, going cheap on the skimmer and/or lights is a no no....although I'm sure some will disagree
As for sump layout, I prefer: SKIMMER -> RETURN <- REFUGIUM
If you have room for a seperate refugium, that would be nice to.