I've had this Chinese Elm for just over a year now (my first tree, so be kind ) and it's been doing well. I'm currently keeping it as an inside bonsai as I have no outside space at the moment sadly, I do hope to change that though. As it starts to regrow this year I was looking into styling it, watching tutorial videos etc. and one of the main topics is following the trunk and styling around that. This Elm was bought from a nursery and it looks like the top main branches from the trunk were cut off before I purchased it.

Does anybody have any guidance on how I should approach pruning and styling this tree? I'm also having a hard time keeping leaves in the middle of the tree, would pruning back hard remedy that?