To make your billboard(s) looking more realistic, I would suggest you to work on its material(s) - you could add Normal Bump
map / Displacement
map to archive it. There are several ways how to get these maps (like from 3D objects), but as it's quite complex process, there is no automatic way for it in Forest Pack and it needs to be done "manually". Also please note, there are several billboard templates
inside of Forest Pack for use in various situations.
In case of using one-plane billboards, the Look-At
feature (under Camera
rollout) could be very handy (rotates the items to look at a specified object - the camera or other node from the scene).
Hope this helps you a bit.