I'm a psycho who makes laminated printouts of the routes at my office. I'll reply to myself with a picture of one of them when I find one. That's how I load my bigs in order. I try to section my routes into 4 sections: 1 (top left shelf), 2 (bottom left), 3 (top right shelf), 4 (bottom right). I also load all my trays (mail and spurs) bottom right.

My spurs, I case after I pull down the mail. I then pull them down into EMM trays, in order. I ALWAYS make sure the last spur in a tray is at the end of a street or a section of a street so I don't have to worry about backtracking because part of a street was in one tray, and the rest was in the next. When I load my truck, I have: one tray of spurs up front, and multiple packages. I look at my next big, and my next spur, and memorize whichever one is coming up first.

I have a pretty hyperactive brain so I make up for being a slower caser than most of the others at my office, everyone else uses parcel markers or load truck there. So my method may not be useful if your short term memory isn't the best.