Jpeg? Really it should be Png. But putting that aside i think its rather empty. So i think that you should put some more 'effects' in it.
Not Really The Renders look rather hard to use and im not really a large art person so i dont have a large range of effects you could use. Sorry. However try a outline of the renders and some more colour? Test out a gradient map and just anything u think could help. Theres some great vector effects out there Sorry for the lack of help im not in that range of work.
the top render looks like it has alotta shadows/light in it, you could possibly accent that better. i really dont know how to help here sorry. its a start though.
