in FW, aquascaping is big..way bigger then I have ever seen it in SW. A "formula" get you 80% of the way. Some are more creative and do very well breaking rules, but newbies tend to have high success getting something pretty good by using the following
1) golden rule Roughly 2/3rds focus. you can play with either/or/both the horizontal/vertical planes
2) layout as central mound/central valley or triangle.
3) odd numbers. This usually applies to if you have sub "mounds". if so, do 3,5,7 of them.
I know it is freshwater, but there are a ton of good examples of the above in practice
http://showcase.aquatic-gardeners.org/