Don't lie down after eating; give your body time to digest your food. Remove high-fat, processed foods, and fast foods from your diet (this will have a side benefit: weight loss). These foods stay in the stomach longer causing an over production of acid.
Add as much plant protein in your diet as you can, and cut down on the hard-to-digest proteins like meats. You don't have to eliminate meat from your diet entirely, but you could do without eating it every single day, three times a day.
I know how painful living with Acid Reflux, Heartburn and GERD can be. I've suffered these complaints since I was 17 years old. I've had tubes down my throat and up my butt to find the solutions. I've taken Tagamet, Zantac, and Prilosec, Tums, Rolaids and generic Antacids and all any of these things did was to temporarily mask the symptoms.