This blog post by Bon Appetit's Andrew Knowlton offers these "10 rules for making nachos." From what I can see, they seem like sensible rules worth heeding. Here is one of them:
Don't buy pre-grated cheese (ever). Grate it yourself so that the cheese will be fresh and finer in texture, which leads to uniform melting.
I prefer guacamole or salsa to nachos-and-cheese dip, but I realize I'm swimming upstream on this one. I was lucky enough to be at last year's Super Bowl. I hope this year's game is even half as suspenseful as last year's 4th quarter was.