I can't tell you what to do, just do what you want...You just have to find your ideas yourself
Just fix a list of things you want to improve, and start something wich will make you work a lot to clear your weakness.
It's the way i work when i don't know what to do
For exemple, if you have troubles at organic modeling, try to do some , as a realistic human face, or a ugly monster, etc... something wich sounds fun and wich will make you work.
I hope you see what i mean.