If it's your first time trust me you'll miss plenty. :eek:
Do you know if you'll be shooting "real" sporting clays or five stand? Either way no one choke is likely to be best. If you're gonna stick with one only tho I'd go with IMP CYL but often a MOD is very helpful. Sporting clays more than any other clays game really is best shot with an O/U and two different chokes at least at times. You'll likely have shots where even CYL seems too tight and some where even MOD might not seem tight enough. Some course try to add difficulty thru distance where others do it with subtle angles and presentation.
You can expect rabbits running along the ground and bouncing like a bunny hopping, targets coming straight at you and going straight away, high targets low targets and some that go straight up in the air.
Just go have fun and don't worry about score. Don't be the first to shoot at any station. Have others more experience shoot ahead of you and watch where the targets come from and where they break them.