A brief writing on design principles you can apply to aquascaping
http://flowerandmonster.com/index.php/a ... proportion
An aquascaping tool so you don't have to pull out a piece paper and pencil
http://www.2noodles.com/tank/organizer.html
Here are the different styles made with the aquascaping tool.
Iwagumi Style
tip: Use odd number stones. Have a clear hierarchy where there is a central large stone. The smaller ones support the main stone. And the key with this style is simplicity and to achieve a natural harmony. This mimics a mountain scape against a seashore.
Dutch Style
Although it has fallen out of fashion, it's still visually interesting and challenging.
tip: Dutch style is about grouping and manicuring the plants in an ordered almost geometric fashion. It's the western concept of nature as oppose to iwagumi or any of the naturalistic styles. Variation in textures and colors on the plants are also important in this style.
Natural Window
There aren't any formalized rules for this but in essence, it should feel like if you were to take a snapshot of an underwater scene.
River Biotope
A biotope is the most natural and strictest of the styles.
tip: You can only use elements that are found in this habitat. Since rivers are fast moving, only smooth stones and low growing plants like moss are dominant. A little leaf litter adds to the natural scene.