i think it somewhat depends on your fish selection.....
There are 2 major ideas that I have tried, one is to make like a wall, the other is to make piles. Both look nice, just depends on what you have and what you like.
If you have fish that will like to hover around the sand then you might want to make large piles so that they can have more room to swim around the bottom. This also opens up the tank for more swimming room for fish who swim a lot.
If I were you I would look at a bunch of pictures in the photography forum and see what you like. Ultimately this is one of the decisions you get to make on your own, just do it so you like it.