Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
In a cube shaped tank there is the option of doing a symmetrical layout, the hardscape centered in the tank. This could be a rock, some wood, or it could be a specimen plant. It does not have to be done that way, you could still use the golden mean to lay out the tank.
12" is small.
Stick with a minimum sort of set up.
Choose either driftwood OR rock, not both.
Choose just a very few species of plant. Perhaps a ground cover and one species of taller plant. Maybe a 3rd species, perhaps red leafed. Small plants.