If the hinges are loose in the pins, you will want to take care of that first.
Did you get an original door? I have heard that the reproduction ones aren't as good. No personal experience.
If the door sags when you open it, then the striker is pulling it up, which is hard on it and the latch. The hinges have to hold it at the correct height so that it doesn't drag on the striker pin so hard.
It sounds like you need to loosen the hinges on the body side to move things around. Backwards a tiny bit, and down on the front. Probably have to take the bottom hinge backwards to raise the rear of the door up a little.
I was taught to take the striker pin out, and also remove the door seal is the best way to adjust doors. I don't do it every time, though. But I don't do body work very much either.
Check the gaps all the way around the top and the back. You have to make the door fit the cab. You can move the fender around to fit to the door.
I don't know any "tricks" to help though.
