Advices for newbie here !

Hey guys I am new member here , I have some experience in dealing with wordpress and I have building some advanced wordpress themes for clients , also creating some scripts with php and mysql .

I have been decided creating wordpress theme here in themeforest , can plz advice me to make me avoid Re-Invent the Wheel !

1- what’s the best framework can i use ? 2- How can i get accepted ? 3- what I should learn before starting creating like languages , techniques , ... etc ? 4- anymore advices !