As an ex-reflux victim, i can report only good experiences with raising the head end of the bed by an inch or less.
Of course, you should sleep on the back, possibly without a pillow.
Lying on the stomach is a no-go.
Lying on the stomach side puts stress on the stomach, only when it is not empty, but the reflux is generally eased, because the esophagus is in a slightly ascending position. Doing it the other way might feel better, but is actually worse in terms of reflux.
But that's only for easing symptoms. Then it's time to get to the root problem(s).

Generally, don't mix carbs with fatty food too much, it takes way longer to digest.

And there's a tip from the experts: Try eating slow by chewing longer. After about 20 minutes of eating your body should signal saturation, pretty much independent of how much you ate. This way you train yourself to eat more often, but don't fill up your whole stomach each time. I used to eat much, very fast, when i was younger, and that's what i blame for getting reflux problems.