A non slip strip and it's small size works miracles. This tiny strip attaches underneath any strap to stop slipping, sliding and falling straps.
Strap Doctor Anti-Slip Strips
BeConfident Racer Back Bra Clip 3-Pack
Pink Tree - The Fitting Shop
Strap Gummy - Prevent Strap Slips - The Original Non Slip Shoulder
SHOP ALL BRAS – Lily Pad Lingerie
Strap Doctor Non Slip Shoulder Cushions-The Cure for Sliding and
SHOP ALL BRAS – Lily Pad Lingerie
Strap Doctor STRAPDR Forever Yours Lingerie in Canada
Straps - Accessories: Clothing, Shoes & Accessories
No Slip) Bra Strap Holder
Strap Doctor - Anti Slip Strap