reed some books, I liked the complete whitewater rafter. Also, have and learn how to use a throw rope, z drag, perimeter line, flip lines etc. get ready to rig to flip and flip back over. Are you going to do both paddle raft and row? if so, work on both in a controlled environment like class II or a lake.
Take a guide course if you plan on changing out your raft cattle, inexperienced people will tax you mentally and some will panic. you should know how to deal with this as well. Be the strongest member and encourage others to be strong and not panic. paddle often with other people that paddle too, bring competent people to the river and lessen your chances all together, educate those you bring to the sport and keep safety #1 and you will last a long time