Important Tips For Weight Gain

Stay away from bad fat! Even though weight gain is your goal, you don't want to be gaining fat and eating junk. Get rid of the chips and candy. No more fast food, nothing fried. Stick to high protein, low (saturated) fat foods like fish (and fish oil supplements), chicken breast, turkey, lean meats, rice, pasta, fruits and vegetables, nuts, flax seed oil, etc. (For more information, go here: Diet Plans And Diets)

Track your progress! Weighing yourself once a week is extremely important, but so is figuring out if the weight you are gaining is muscle or fat. In order to know this information, you need to also track your body fat percentage!
WATER! Drink water! Drink around a half gallon a day, more if you can. Yes that's a lot of water, but it's that water that will give you the energy you need to gain that weight!
Sleep! YES! Sleep! The easiest, yet most over looked step. Get at least 8 hours of sleep a night. You're gonna need it!
Now the concern some people have about how to gain weight, is how to do it without putting on extra fat. Let me tell you how, YOU CAN'T! Unless you are using steroids, it is basically impossible to gain weight without putting on a little bit of extra fat. But hey, you want to see some weight gain right? Well then who cares about the little bit of extra fat you might put on while gaining. You will be able to burn that off later on, right now gaining is your main concern, so that is all you need to worry about.