Start with something very simple like pong or pacman.
Just try to keep them simple and clean and then you can add features if you want to or just start with something more complex.

And if you haven´t done it yet, read a lot of tutorials. I read tutorials for about a half year until I was able to really script something on my own, but the many tutorials I read at that are still helping me cause I got to know a lot of ways to get things done and am know able to write (at least that is my opinion) some simple and selfexplaining scripts.
And if you don´t do it yet, use the manual all the time and if you look up something, also look at all the similar stuff to get to know everything.
I nearly never know how to use a function but I know its name and how to find it in the manual.