Off the top of my head:
#1. Get the necessary tools for the job - 1 good playing cue and 1 good jump cue.
You can learn a lot with a bar cue, but they play differently (and generally worse) than a good production
or custom cue.
There's tons of cues that fit the bill and people will argue it to death. If you want just
one guy's opinion: get a predator or OB cue, or at least get one of their shafts and put it on your existing cue.
Optional: get a decent break cue. It's not 100% necessary, I see many pros break with their playing cues.
If you're breaking correctly it won't damage the cue. It will shorten the lifespan of the tip and you'll have to have
them redone eventually.
2. There's a million free articles, tidbits, and instructional videos on this site:
http://dr-dave-billiards.com/
IMO this info is best because it's carefully tested, and fully explained. You'll hear a lot of bad advice
in the pool world in terms of instruction, stuff that's superstitious, or stuff that the instructor doesn't
understand but they insist "it just works trust me". There's a goldmine of info on the site for free
if you have the patience to look for it and read.
3. Get good books such as 99 critical shots. I think they pack more info for your money than any DVD.
The book on the Dr. Dave site is worth getting.
4. Get good DVDs anyway. Mostly instructional but also match DVDs to help with strategy.
The VEPS series on that site is good. Accu-stats.com is good for match videos.
5. You can gamble or enter tournaments if you want, but don't think this is the way to "learn pool".
You won't learn how to spin a ball off the rail or make a bank shot or whatever this way.
This is the way you train yourself to handle pressure. Pressure can take your best game
and turn it to shit, if you don't learn to deal with it.
But first you need to develop "your best game" before you start worrying about
how pressure can wreck it. That means knowing what you're doing, understanding
how to control the cue ball, the effects of english, how to hold the cue correctly,
how to line up and aim, and so on.
6. If you have the money, get 1v1 lessons with the best instructor you can afford
(or the best within reasonable driving distance).
7. Practice x 1,000,000 ...at this point you have info from books, dvds, and instructors.
The knowledge part of the game is pretty easy. But you need to be able to execute
what you know. Not too many shortcuts for that... just practice. Take advantage of specials
at the pool hall to practice for many hours for cheap. Or buy your own table.
Don't confuse playing with practice, but when you DO play with friends, don't be afraid
to sneak a little practice in there by trying new things.