When the stomach is full and expanded, it makes it that much harder for a faulty LES valve to operate properly. This is one of the main reasons reflux occurs most often after a meal. (This is also why reflux frequently occurs during a pregnancy.)
For this reason, GERD sufferers should skip the gut-busting feasts and alter their eating habits to feature smaller meals (even if you have to eat four to five light meals a day, instead of three square belt-looseners).
Wearing looser clothes can also help relieve some of the pressure on your stomach. And silly as it may sound, try not to bend over after eating, as this will increase gastric pressure and possibly force stomach acid up into your esophagus.