[Mo123]

Are there any good and understandable RP gamemodes or any other that would help me on my journey to become a decent scripter?

[Kane]

https://sampforum.blast.hk/showthread.php?tid=641235

Once you go through enough of it, while also learning what you don't know from the Wiki or whatever material you use to help you, you'll end up getting the jist of it really.

[TakeiT]

I found the best way is to simply start doing tutorials. Especially since RP gamemodes are generally pretty complex.

[Sew_Sumi]

If you have coding experience, ignore the above.

Reading code is a good way to start understanding the setup if you are a coder of any sort already.