Here is my advice, take as needed. it may not work for you but it sounds good to me.
If you can afford an instructor get one(they are expensive), if not, read a bunch of books on the subject. Either way you go, you should still read all the books you can. I never had an instructor. It feels better that way to me. It makes me feel great to know I accomplished something on my own. Without help.
A great website to check out is Ultimate-Guitar.com. It has all kind lessons, reviews, news and videos. It also has tabs for any song you can possibily think of (millions of them). The people in the fourms are great and they can help you with anything you need or any other questions you might have. Just ask nicely.
Any good starter package from Musiciansfriend.com or Guitar Center is all you need. You don't want to spend good money on a guitar then figure out that you dont wanna play anymore. Once you feel confident about yourself and playing then drop some money on one if you want.
The number one thing in my opinion is to always play in tune and check it often. Cant stress this one enough. If you play out of tune it will not sound right or feel right. Get you guitar set-up properly by a professional. It will feel, play, and sound better if you spend the few dollars to get this done. It is also solves one of the most common problems with the guitar sounding out of tune when it is in tune. Most people overlook this, but I can't. There is nothing worse or harder then trying to learn or play on a guitar that not set-up properly and in tune.
Learn how to properly tune a guitar. Start from the bottom and go to the top and back down then back up and so on. repeat this untill all strings are in perfect tune. Always tune up to a note, never tune down to a note. example if your guitar is in standard tuning(EADGBe) and you want to drop the tuneing to either a dropped tuneing(DADGBe) or just go down a step(DGCFAd),first tune the string lower then the note you are trying to tune to, then tune up to the desired note. Once you are finally in tune, strech and bend your strings by playing for a few minutes to warm them up. If you have a whammy bar, throw in a couple of dive-bombs and then retune. If you do this it will keep your tuneing more stable.
Learn to feel the difference in the neck of your guitar when it is in tune and when its not. an example is, sometimes it may be slightly out of tune and you can feel that the neck vibrates differently than when its in tune.
Learn the placement of all the notes on the fretboard.
Learn all of the basic chords.
Learn basic scales and chords in different positions on the neck.
Learn how to use a metronome. start at a slow speed and work your
way up. this helps alot with your tempo,timing, and to stay consistent with you playing.
Learn as many different finger exercises to keep your fingers strong.
Learn to play different styles of music and not just one style
Learn to play in different tuneings and keys
Learn all of the terminology like hammer-on and pull-offs, slide up or
down, palm mutes, string nutes, harmonics and pinch harmonics, bends and pre-bends and others.
Learn how to count beats and measures with a metronome.
When i play i like to warm up first doing basic scales with all kinds of different picking patterns and slides to get my fingers going up to speed. For example. up down. down down. down up.
If you play on a good practice schedule you will improve on newer playing styles and playing ability. Haveing a strict practice will make or breake you.
Don't let yourself get aggrivated at one thing. If you cant get one thing down move on to something else and just try it later.
I hope I have helped you out some. I may have skipped some things but you will figure alot of it out by yourself with time and practice.