First piece of advice, make sure you pay for a decent guitar. Do not go cheap and get something that is not playable. Make sure the intonation is correct. People sometimes make the mistake of thinking they'll buy something cheap and upgrade once they learn a bit. More times than not, they simply get pissed off due to not being able to learn. Often times, it is the guitar that will not sound very good, or the strings are an inch off the fret board, or, as I mentioned, the intonation is off. no matter what skill level one is at, they will sound terrible with these factors. Could be very frustrating.
Anyways, I'll speak a little more on intonation as this, to me, is something that drives me to trash a guitar. This is also something that an inexperienced buy/player may not know about. Basically, it is having the guitar in tune with itself. If the intonation is not perfect, your guitar will sound in tune at the lower end of the neck but sound out of tune as you move higher up the neck. This will mean that know matter how skilled you are, it just won't sound right.
So, before buying a guitar, hold it, strum a few chords, even if you don't know any, just to see how it feels. If you feel like you are fighting the strings in order to fret them, this probably is not the guitar for you as you will have fits trying to learn. Then, make sure the intonation is correct.
How to check the intonation: Strike an open string (strum a string without touching it with your non picking hand) which will obviously sound a pitch. Now sound the natural harmonic at the 12 fret of that string. That pictch should be exactly the same. The untrained ear will need an electronic tuner, however, if you have a bit of an ear, you will be able to hear the difference, if any. Could go on all day on this stuff and recommend it as once you truely learn to play a song, it just takes you away. Then playing with others (bass, drums, etc) takes even beyond that, so, good luck.