Maybe take a guess, watch a lesson (they are just around 10 minutes) and see if you need to go to simpler of more complex ones? I think it depends too much on

Maybe take a guess, watch a lesson (they are just around 10 minutes) and see if you need to go to simpler of more complex ones? I think it depends too much on what you already know, what concepts are you familiar with and what you really want to know. But I guess not even you could be sure about that, so go explore some.