The best advice I can offer is that you will improve in sudden, unexpected bursts. Meaning, literally, after six months of seemingly no progress, you will one day stumble into some new thing that will open up a whole new world of possibilities to you. My point is, keep at it, even if it seems you aren't progressing. And experiment often. Some of the most highly regarded modern guitarists play the instrument in all kinds of stupid ways.
Remember the four frets/four fingers theory. I.E., try not to waste fingers. If you have your index finger on the second fret, and you need to go to the fourth fret, use your ring finger. If you need to go to the third from that same position, use your middle finger. THe fifth fret, your pinky.
Understanding that concept is vital to playing down the road.
Learning the methods in other people's songs is more important than actually successfully emulating them. When playing another person's song, try putting your own spin on it if you like--always be creative, never limit yourself, or you will quickly become good at five things and be clueless about the rest.
That includes speed picking and all that other crap.
There's no such thing as an unhealthy influence.
Always keep the guitar tuned, even if you have to rely on an electronic tuner. Without a consistent tuning you can be playing any tab or song perfectly right but it will sound terrible and you will subsequently make no progress.
Hit the strings hard enough to get good attack, but let the pick flex; if you're holding it tight enough that the strings are giving you a lot of resistance, you're either holding the pick in an off way or the strings are too tight.
Chords are an excellent starting point but they can be hard for an untrained hand to grasp. I recommend starting with power chords, the simpler shapes that you can learn to move around the neck. That gave me a better understanding of rhythm and melody than the chords did. Once your hand is a little trained tackling the chords is a lot easier.
There's a lot more tips I posted in another guitar thread awhile back, if you feel like searching. But the most important advice is this: don't listen to anyone who tells you how to play.
