Make sure you've got your wheel/pedal setup correctly in terms of ergonomics i.e. so that you're not forced into any type of awkward posture when using them. Now with regards to the pedals specifically, DO NOT brace/hold your foot just above the brake pedal as the default position if you brake with your left foot - rest your foot at the side so your calf muscles aren't in constant tension, and move your foot to the braking position only when required. It takes some getting used to, but once you're accustomed to it, it becomes second nature.