I don't want to spark debate over the safety of using headphones while riding, but if we presuppose you have made the decision to wear them anyway it becomes helpful to have an easy way to control volume and playback. I've tried a few odd things but ultimately this was the best result: Chubby Buttons.
Odd name, but effective. They are marketed largely to snowsports folk, so the buttons are large and distinct from one another. Easy to find them by feel even with thick gloves. There isn't a super convenient way to attach as sold. You could strap it to your right forearm and reach across. I opted to cut away the sticky foam on the back and use a heavy duty outdoor adhesive to affix a RAM ball. Pretty reliable in terms of Bluetooth connection, and doesn't go into deep sleep for 8 hours, so it doesn't constantly have to reconnect when you go to use it.
Just thought I'd share what's working for me.