Protein with milk or water?

I started using protein from GNC lately for football because my Coach wants me to get a little more bigger and bulky for my position(CB/FS & WR) because I'll be Varsity but keep or possibly even get faster because I run a 4.8. The guy at GNC said get Amplified Wheybolic Extreme 60. It says on the bag take three scoops mixed with 12 oz of water. I did for the first few weeks then started using milk instead. So, for this particular protein, if you know or have taken it before, is it better to use with water or milk?