There are generally two approaches to designing a bonsai tree in terms of character. These two styles can be characterized as either having strength or elegance. All the components of a good bonsai tree contribute to the style including its roots, trunk, and branch arrangement (structure).
Bonsai trees that exhibit strength tend to feature strong thick trunks and roots. The height of the tree is also kept limited in order to compact the tree and give it a more solid and stable appearance. The branches are arranged in a zig zag pattern that push the growth back toward the trunk and give the tree an all around depth and fullness.
On the other side is elegance or portraying your tree to have a slender appearance. Most commonly used in Bunjin or literati style arrangements, the trunks of these trees are tall and narrow. The branch structure runs alongside the trunk movement in a wave like appearance with no hard zig zag curves. The overall effect is a thin slender appearance that is soft and flowing.
Determining the style for your tree is usually determined based on the tree’s movement and natural inclination. Certain tree shapes lend themselves to a particular style. By studying your tree and identifying it’s movement, you can see which style best fits your tree.