I use a 50d with a Canon 400/5.6. Usually Manual, f5.6 (this lens is great wide open,I used to use a Sigma 150-500 at f8), shutter speed 1/1000 or more, and whatever ISO makes this work (usually 200 to 400 on a sunny day.) Sometimes I use AV, especially if I may be dealing with changing light. Same f stop, whatever ISO will keep the shutter at 1/1000 in the darker light I expect - so anything lighter puts the speed higher. I set the camera on AI Servo, continuous shooting (I normally shoot bursts of at least three shots) and center point focusing.
Practice a lot, take lots of pictures, and don't be discouraged by a low rate of "keepers."