First, I wouldn't attempt to move an aquarium unless its empty. And, I mean literally empty -- don't leave any gravel, stone, wood, or anything else in it (a little bit of water can add a lot of weight but is undamaging). I've seen people try to move a tank with a rock in it, and one wrong move and ... crack.
Make sure the tank is well strapped in to any handtruck, and make sure that someone is keeping it on there. It sucks when you drop a box off a handtruck, it really sucks when that box is made out of glass.
When putting it into your truck, make sure that the bottom is down. Don't set it on a side -- especially if that side is going to become your front. Put something between it and anything else -- you don't want it to move a little bit on the drive over and scratch.
Suction cup handles are a godsend.
Try to carry it levelly. If the weight distribution is off, you can wind up twisting it, which can damage seams, or worse. Minimise the time its being carried, too. This isn't just smart for your back, but good for the tank. Furniture dollies can really help.