What should I do after completing all the modules to make my skills stronger?

Answer 1

practice?

Answer 2

You can either practice by writing the first algorithm that comes to your mind or learn another programming language

Answer 3

play challange and write code!!!

Answer 4

How?

Answer 5

You could answer others questions or look up Python problems like:

convert binary to string

return wether or not a string contains a substring without using find(), etc

Then you could try to build a program that solves those tasks in the code playground. I'm not sure what else you could do.