General statements I would make would be as follows:
1. A way to get more head is to carbonate to higher volumes. If priming, add a bit more sugar than usual. If kegging, add a bit more gas than usual.
1.a. Better head retention would be a combination of factors including but not limited to, check your fermentation (yeast pitch rate, temperature, etc.), possibly add higher-protein adjuncts if you deem it necessary, ensure your glass is clean when you pour your beer (no detergent residue or the like), pour your beer correctly, if necessary use an etched-bottom glass.
2. More body would normally be attributed to the addition of higher unfermentables in the beer. Some add Malto-Dextrin to add mouthfeel and the like. If brewing all grain, try brewing in a slightly higher temperature range to create a slightly less-fermentable wort (with a higher FG) or even try using a lower-attenuating yeast strain.
Then again, I don't know if any of that really matters. I've just had good luck with getting awesome head retention on my beers.