The first day I got a guitar, I played it for like 8 hours. I lost interest for a while, but I got inspiration and I love it again.
My biggest tip... get lessons. There are shit bands on TV that play 2 catchy coords and are recognized over great bands that aren't noticed at all. Learn music theory. Learn scales. Compose GOOD music. Don't immediately want to be a star and end up becoming a cheap sellout if that is where you want to go.
Get a beginner guitar, like a slammer. After a year or two, upgrade. I have a Hagstrom atm, I love it.
And mostly, have FUN.