i dont claim to be an expert but maybe what i have to say might be of some use to you.
"small bonsai donot become large bonsai"..... your tree tunk should be as thick as you want it before you transfer it into the bonsai pot because bonsai pots drastically retard growth and trunk growth for that matter. so its best you plant your tree in open ground or a bigger pot.......
if you tie a wire ( or sturdy string) around the base of the trunk it will swell from the place you tie the wire and up..... you should tie the wire firmly but be careful not to tie it too tightly or you could kill the supply system of the tree(killing the tree).
never soak a bonsai tree to water it.... you should always pour the water into the soil.(the salts in the soil tend to get disturbed)
other than that heres a link that will help you
http://www.evergreengardenworks.com/trunks.htm
my advice is given hoping you will benifit from it and i hope if i have made any mistake the other guys on the forums will correct me.