[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] ahagersr:
I'll post you some links here in a little while, as deceptive as my post count may be, I used to be known as smoothtaste here on XDA (and later on as ahager88, then I went on hiatus when I had my little Junior)

Ultimately the best thing for you to start out is familiarize yourself with Git. Git commands will be essential. Read up on those, and download source from a developer that shares your device tree, faux123 or ktoons would be good, whoever you prefer. Preludedrew used to have a wonderful guide setup on the Evervolv site for building his rom from source, you can read his guide for excellent information regarding getting your environment setup and workable.

Once you have your environment setup and understand how to change variables and build with the make command, you can make small changes as you learn them, such as incorporating different governors into the build, etc, build it, flash it on a rom that the kernel will be compatible with and see your changes.

All of this is nothing in terms of development, however. But it will get you in the swing of things that you'll be doing a lot. If I forget to come back and post the links just pm me, I've got a lot of good reading material bookmarked on my machine at home.

Sent from my SAMSUNG-SGH-I747

---------- Post added at 12:41 PM ---------- Previous post was at 12:35 PM ----------

https://github.com/Evervolv/android/blob/jellybean/README

Don't jump in and sync the Evervolv source, but everything in that readme pertaining to setting up the environment is a must. He has all the necessary libraries listed right at the top, I guess you could sync Evervolv source just to see how Git works as well, but it won't ultimately help you with our device. Again, I will make a point to provide you with material closer to what you're asking for as soon as I have the chance.

Don't ever be afraid to ask for help around here. You might get some people who are demeaning and think you should already know everything from time to time, but good people come along.

Sent from my SAMSUNG-SGH-I747

---------- Post added at 12:58 PM ---------- Previous post was at 12:41 PM ----------

Be warned, some of this is outdated, I know one source mentions Ubuntu 9.04. I know a few people that use 12.04 still, and some that use 12.10, Ubuntu is the easiest OS to setup with, I have done it with Fedora, and Arch Linux has always been my favorite but you should probably stay away from that. You have to choose the files/libs that are needed for your distribution, and the fetch commands change depending on the OS, as well as of you're doing 32 or 64 bit.

Basic Kernel Material

http://kernelnewbies.org/FAQ

http://www.ibm.com/developerworks/library/l-linux-kernel/

http://en.m.wikipedia.org/wiki/Linux_kernel

http://www.tuxradar.com/content/how-linux-kernel-works

http://www.howtogeek.com/howto/31632/what-is-the-linux-kernel-and-what-does-it-do/

Building/Modifying Kernel Source

http://source.android.com/source/building-kernels.html

http://xda-university.com/as-a-developer/getting-started-building-a-kernel-from-source

http://xdaforums.com/showthread.php?t=1748297

http://simply-android.wikia.com/wiki/Kernel_Development

Att Galaxy S3 Related

At the present I do not know of any guides or materials pertaining to this device solely, though this doesn't mean they aren't out there. Once you get the hang of things working with the source of your choosing, it won't matter anyway.

Sent from my SAMSUNG-SGH-I747