I was reading the other day, maybe in the new muscle and fitness or somewhere, that one thing that is really necessary for the traditional hard gainers (the ones that could eat a whole pizzza and still not gain any weight). They said to start with more at breakfast and this struck me because of my schedule (and laziness) I have been only having a protein shake for breakfast. I started eating more for breakfast about a week ago and have noticed a difference already. Much easier to get more carbs in each day that way.
Using milk to mix with your shakes is great, it tastes better but drinking a lot will contribute to excessive soreness. All that lactic acid building up in your muscles can make a recovery extra painfull.