Truth be told, starting off with a lighter weighted passenger is going to be much easier to learn. There is not a huge difference, but the lighter they are, the smaller mistakes they make you won't be able to feel. My wife and I have taken many, many trips together on the Stryker. I'd say over 900 miles or so, so far(not huge i know).
1. Can't stress enough how everyone has said - ONLY get on and off when I say it's time. The passenger has no idea if you are going to a complete stop to put into Neutral or waiting for them to get off. You have to be very vocal.
2. Just let them know that the only time to fix that wedgie or stand up on the pegs(meh some like too to help their ass?), is while moving at a decent speed. OR tell you they are going to fidget at a stop light. I can be going 65 and not even notice the wife is moving around, but at a stop light i can almost dump the bike.
3. You aren't a bad ass. You have someone elses life in your hands behind you. The bike is going to be extremely heavy, and they are completely vulnerable. They have zero power to change any outcome of a wreck or oncoming traffic.
4. Lately this is the most important, other than number 1. If you scrap the pegs as often as I do, let them know it's normal. My wife still has the urge to jolt up and grab ahold of me. That is something I do not need. A sudden Jerk could mean a holy **** moment in a turn. It not only scares me, but makes me lean out of the turn sometimes. We are working on it, but she just isn't used to hearing us get that low to the ground.
Passenger relocation pegs and a backrest were a MUST for my wife.