I have wanted to see Tab Benoit for many years. A blues man out of Louisiana who has a passion for the blues, his own history and the history of Louisiana.
To not just play scales for the sake of scales. To play them for music I am learning, and to only do them as part of a practice regime that includes other things.
To work more on making playing fun, then I wouldn't have had to force myself to practice so much. It became to much of a chore (See number 1 about scales!)
To realize that listening to music and becoming a musician is as important as being able to play the guitar.
To work on playing slow in order to play fast.
To keep the guitar high and at 45 degree angle so as to have a relaxed posture without too much wrist bending.
That playing guitar and music in general is a life-long pursuit, and you will always be learning no matter how good you think you are.
To always study a little theory and see how it fits in with what songs I am playing so I can understand them more.
That I didn't have to and really couldn't learn everything about theory by reading a book. That I needed to play it to learn it.
To practice in small doses instead of one long practice. IOW, five or six 15 minute practices a day versus 2 hours straight through.
To practice a little every day of the week instead of just one long practice on the weekend.
To work on more than one song at a time.
Have as much fun as possible.
Don't answer any top-ten list requests because I can't count.
Buy a guitar that feels and sounds good to you. This may be difficult for a beginner, so if possible take along an experienced guitar player to check out action, intonation, etc. and let that person play and see how it sounds to you. If you don't have such a friend, I suggested you buy from one of the smaller, established music stores in your area. One of the knowlegable sales staff can help with these things.
Buy a decent electronic tuner and keep your guitar in tune. Practicing with an "in tune" guitar provides positive feedback while an out of tune one does the opposite.
Get some good beginners' guitar books. I like the Stringletter Publishing (Acoustic Guitar Magazine) "Basics" Series and "Uncle Tim's First Year".
Practice regularly (every day if possible). I like a few short sessions.
Don't try to race through your first beginner's book (like I did with Guitar for Dummies)thinking as soon as you finish it you'll be a "guitar player" (you won't!!). You need to repeat the basics over and over and gradually add new things.
Practice scales, chords, and songs. Uncle Tim's First Year does a good job of tying scales to corresponding chord formation and the chord progressions that go along with each scale. This will greatly help you figure out the key of songs you wish to play and what the chords of the song are likely to be. Also, when you get reasonably good, this can be the basis for some original songwriting as well (if that's your bag).
Practice with your friends, the more experienced the better.
Get a recommendation from that local guitar shop for an instructor that is right for your goals and music type and take some formal lessons.
Participate regularly in a good guitar newsgroup (like this one!).
And last but not least, did I say practice, practice, practice .......