I feel like a total noob. I have always owned shoulder bags with 1 long adjustable strap so since I have being buying new bags for a little over 2 months, I have been learning how to hold the different styles. I know it sounds daft as a woman of 39 is learning how to carry a grab bag. Any way, I dont have so much the problem of slippage, more a problem of pain in the bend of my elbow where the straps have been resting. It gets really painful as Im not used to carrying a bag that way. Them gel heel pads would be great for slippage, or some of that grip stuff you buy on a roll.