hey dude;
You already got some great advice - here's my 2 cents:
DIET is key - figure out what you need to eat calorie wise and do it. Also look for the best choices for growth in terms of carbs, protein, fats. Don't eat crap (You know - anything sweet or fried or tastes REALLY good...LOL) and take the budget you would put in roids ($500+)? and put it into a trainer who knows his shit. Don't go for a cutie pie at the gym or someone who is your "friend" go for a guy who has been there and done it.
Best of luck - work hard.