As a previous poster mentioned, having the PAL labels out is not only a "method", it is a good idea - it not only helps the loader find their own misloads before/after they happen, it makes the supervisor(s) job easier because they can walk through the truck and quickly find any obvious misloads. Also, blend the motion of picking up a box, taking off the sticker and putting it in your preferred spot, and beginning to walk into one motion - that is to say, don't stand still, grab the sticker, so on and so forth; have the sticker on the box before you even get into the truck. With some practice, you don't even have to look at the box anymore, you can "look before you step" hehe.
A final note on the PAL labels out - it really helps keep the stops together; no one can remember where they put every box in 3+ trucks unless some labels are facing out. Your drivers might appreciate it, too.
Pick up multiple boxes; don't tuck one under each arm like a football - instead, carry them in a stack close to your body. If they are light, put the slaps on the boxes with your free hand; otherwise, put them where they belong in the truck and when you have a second, put the PAL's where they need to be.
Move fast; obviously, don't run, but if preloading could be done at a leisurely pace, then anyone could do it - the turnover rate seems to signal that not everyone can do it - for many reasons, I'm sure - but one of those reasons is that some people don't want to move fast and sweat hard.
Use the back shelf; unless the box is pretty long, there is a ton of room back there. Use it, as it helps keep the stops together.
Move bulk stops to RDL/RDR if there is nothing there, or only a few small boxes there; tell the driver.
Unless there are mitigating circumstances, be friendly with your drivers. You work hard, they work hard, and it is a synergistic relationship.
Depending on what type of person you are, eat and drink properly; if you eat 5 cheeseburgers and drink ten beers, your performance will suffer the next day. I am not a nutritionist, but taking part in such activities on a day when you have to get up at the butt-crack of dawn and do physical labor for 3.5+ hours seems like a bad idea.
On a personal level, I always took the job personally; when I did a bad job, I was slightly mad at management for maybe expecting the impossible, or IE for being ... well, IE; but mainly, I was mad at myself for not figuring out a way to get the job done. And I would tell the drivers - "Sorry, I did a bad job today." Psychologically advisable? Maybe not; but it did constantly push me to find better ways to do the job, at which point my preload shift became hard work, but where I was almost never behind. I would move around and help others, because otherwise I was standing there with nothing to do.
To summarize, in my opinion, the three things that will help almost any preloader (taken from the methods) are: walk at a brisk pace, optimum carries, and PAL's facing out. Learned properly, they made my life so much easier as a loader.
Good luck, and be safe.