L293D Heat sink ?

So I’m planing to use L293D on my coming up project and as I understand it gonna
heat up a lot, my motors that I’m gonna use come up to work from 3v~6v~12v with the current of
80~150~300mA.

I’m a newbie at picking up heat sink can you tell me how do I calculate and pick up the right heat sink?
I don’t want to come up with a chip explosion or burned chips :smiley: I heat something about C/W or something like that.

D.60