I'm going to make some garage shelves. My plan is basically to replicate what this guy did: http://davewirth.blogspot.com/2013/0...-basement.html
only, instead of the "legs" being on the short edge of the shelf, mine will be at the ends of the long edge. The plan is to build all the boxes for the shelves, then attach them all to the legs. Here is a top view:


I am running into a very basic problem though. How the heck do I build this box square? I have a speed square to place everything where I need it to be, but when it comes to drilling my holes, I can't hold everything in place. Should I consider doing it the way the guy in the link did, where he builds ladders first? It seems like it would be easier to square longer boards, as their weight will help keep them in place. This seems like a very first day type of question, and kind of embarrassing to ask, but how is the correct way to do this?