ABC's of reloading should be mandatory reading before anything else - good, easy to read overview
Then pick up at least two reloading manuals. As a rule of thumb, at least one should be associated with the bullets you plan on using (like hornady or sierra or speer etc) and the other can be more of a general reference like Lee Reloading manual (cheap and tons of info) or something from Lyman. Lyman has a big comprehensive manual and then more specific books like pistol loads and such. All of these have basic information about loading in addition to the recipes.
Another good reference is Powder Profiles. This is really helpful when trying to select a powder, since it focuses more on the best uses of specific powders rather than being tied to a particular bullet. It is a compilation of monthly reviews from Handloader over the years. An interesting feature is that the older powders like Unique have multiple articles in the book, so you can see how loads have changed over the years using the same powder.
Then there is another called Favorite Loads or something like that - can't remember who the author is since I am at work. I use it, but not as much at this point. I have only been hand loading a year, and expect i will have more of an appreciation for this one as I grow as a reloader.
Being the information junkie that I am, I own all the above mentioned books, so I can vouch for their usefulness.
But the initial keys are the ABCs (recently revised) and the two loading manuals. As has been mentioned above, start low (but not too low) and work your way up to the sweet spot. However, when you select your powder/bullet combination, and before you load the first case, it is very, very important to cross reference any selected load, including the case trim lengths, overall cartridge lengths, and other specs. It would be sad if the ONE you picked had a misprint for the min or max load, and you didn't double check everything before you went to town with the powder.
I started reloading to save $$, and find myself enjoying the reloading and testing new loads to me as rewarding as the shooting
Good luck!
