I only drive sidearm, I feel like my thumb dislocates driving backhand and hurts like hell. I only use a run-up when I really need the extra distance on drives over 400'. For better accuracy I typically use a baseball stance and throwing motion but keep my throwing should low to the ground. I get a lot of torque from shifting weight across the hips and follow through. I vary shoulder height and disc angle depending on the shot and disc. I use two fingers on the inside of the rim and a third on the bottom of the rim with my thumb about 90 degree on top. I would say the champion banshee 172g is the best disc to learn sidearm. My star wraith 170g is my longest disc over 400' sidearm on a flat drive with a run-up. I can't drive anything under 160g with any power because it just turns right over and usually rolls. I prefer stable to overstable discs for straight and hyzer shots. Understable discs tend to turn over and roll with power, unless I put a lot of hyzer on it, then it will flatten out and anhyzer. Understable discs will do a nice helix with less power and standing more upright.
Best for straight/right : Star Wraith 170g, Champ Banshee 172g, Champ Orc 169g, Champ Firebird 168g,
Best for left: DX Cheetah 166g, Star TL 167g, Star Leopard 175g, Star Wraith 170g
I'm having trouble finding a good sidearm approach disc. Any suggestions? I starting to get used to the Star Cro 170g, which is pretty good under 100', but turns over with any power. I often use my Star TL 167g for longer approaches. I prefer discs with a wide rim, but most midrange/approach discs have tiny rims.