I use 5 pillows to support my entire body while on my side:

Two under my upper leg, one behind my upper leg, one at my back, one in front at my upper torso.

I use 6 pillows for support while on my back:

One at each outer thigh, one to slightly elevate each lower leg and one to support each foot. I keep my lower legs slightly elevated to prevent bed sores at my heels. I support the bottom of my feet to prevent foot drop.

I also have a super-soft bed. I turn from my left side to my right side, then lie on my back – every half hour to prevent bed sores.