Preparation Think clamp set up and a dry run. A level surface for your clamps is important, you don't want to introduce any distortions into the panel. I have used the floor for longer panels and the bench top for shorter ones. The dry run will assure that the joinery is correct and that you have enough clamps for the length. This works well for the majority of lengths.
Correct joints is the key.
A properly prepared joint can be glued with no pressure other than gravity. I do not EVER use biscuits in edge joints. They add nothing to the strength of a properly prepared joint. I have always bought time at a shop with a wide belt sander to take care of lots of panel glue-ups and think this is well worth the cost. The number of boards in a glue up will determine how hard it is to achieve surface alignment, only 2 boards, of course being the easiest.