What should we do after learning basic python?

Answer 1

Algorithmic thinking -- it can be boosted by learning even the most simple algorithms. To be honest I think this is the most important thing in coding.

Answer 2

Practice, practice... and practice a little bit more :)

Answer 3

Look for lecture notes on discrete mathematics. Graphs and graph algorithms are basics you *have* to know about if you want to be anything more than a mere code monkey.
If you want to do some practice problems (which you should) you can head over to projecteuler.net right away. There are more than enough problems, some easy enough they can be done with a calculator if you are smart, some of them hard enough to keep you busy for hours or days.