Default [Q] Noob trying to become a dev.

This thread may be pointless but I don't care. I can't find a straight general answer.

I am kind of new to Android modding but have ok skills with coding and decent skills with Linux (I know how to survive in a shell).
What are good code examples or what are the best methods(exploits) used to privilege escalate a shell?
Do I need to find a hole in the Linux kernel or try to hijack an active process running as root?
What is needed to crack the bootloader? I know I'm asking a lot and most of my terms used may be wrong but I find it hard to take that next step. Would I find answers by reading an Android developers book?
Please, where do I start???