We do a ton of reloading, especially since I shoot some more exotic calibers and load to SAAMI, plus it's gets expensive. Loading shotgun shells is pretty easy, loading rifle is a little more difficult technically, but way more interesting.
I use a few different manuals and software, in this order of preference:
Lyman 49th Edition:
Amazon product ASIN B001MYEU0EHornady 9th Edition:
https://www.amazon.com/Hornady-9th-Handbook-Cartridge-Reloading/dp/B00A95QWGM
Lee Precision:
Amazon product ASIN B000N8OKAU
I also use
Load Data:
https://www.loaddata.com/Home
Quickload:
http://www.accurateshooter.com/gear-reviews/test-quickload-review/
And finally, if haven't been on them already, two very, very good forums for shooting, rifles, reloading, development, etc
24hourcampfire.com
accuratereloading.com
Lots and lots of knowledge in all of this material and you can lose yourself for hours going through all the experience, opinions, tech data, etc.
I really got started loading shotgun shells as a kid with my dad, and did that for years before loading a rifle cartridge. I understood the principles fairly well, but had to do a ton of research to determine what powder worked best for specific use, load data for performance, bullet construction, seating, etc.
If you stay close to the recommended load data for each caliber, you won't run into pressure issues, like TCP alluded to.
Some of it is super fun, like learning how to fire form for wildcats, and experimenting with obscure loads for different usage and caliber.