How to start developing/contributing in Mame...

[UnclePetros]

Hello guys,
I'm a software engineer and I'm following Mame from 2007. I've studied documentation, code and tutorial, many times and I've reached a good understanting, but have never had much time to contribute.
Now I want to start to begin to do a further step in rom understanding and mame programming.
Final aim is to try to fix a game I loved from my childhood and never worked on Mame that is Seibu Cup Soccer92.
I know it has emulation problem due to protection not fully decoded, so I know I need much more experience to begin to approach this rom.

So, I want to ask:
Are there other useful resource to start, other than the current documentation present on this forum?
I mean in example, reference to blog of developers active on mame, or detailed tutorial on a simple game.
Something like this (https://wiki.mamedev.org/index.php/Let% ... e_Invaders).
It is a good idea, but is incomplete.

That is, I need some hints from active developers, to start contributing in Mame.

Thank you in advance.

Regards
Petros