Here are my tips for a newbie, from a newbie.
My first tip is to experiment with what works and what doesn't. Obviously you wouldnt want to go and compile your own kernel if your a new guy like me. However, you could start by modifying simple things. Things like the login screen, menu's, custom desktop icons, etc.
My next tip would be to learn a programming language. Depending on what you want to do, you would want to learn different languages. However, python, in my opinion, is a good all around language for learning basic concepts of programming. Things like loops, conditional flow, how an object oriented language is supposed to work, etc. From there, learn the difference between high-level and low-level programming languages. After that, start programming in a different language, one that is very different from what you'd be used to. For me, I started with Python and I now I am learning C++. While I am by no means an expert in python, it's a good introductory language. They say if you know how to program, you can do almost anything.
And linux is a programmers heaven.
Thats pretty much it. Enjoy your linux adventure, and welcome everyone to the tribe of the penguins.
Running on ancient hardware and a mediocre laptop.