Rudderless Sailing Practice - A great way to practice using weight and sail trim is to do a rudderless sailing drill. In the Ideal you can use a spinnaker sheet or any other spare line to tie off the tiller in the center, or bring a strong bungy cord to tie off the tiller in the center. Before tying off the tiller sail out to a place where you have some room. Then tie off your tiller. Then work with your team-mate to set a course and keep it using just sail trim and weight. While sailing a straight line this drill will force you to do exactly what you should do with sails and weight to hold a course. Then try tacking and jibing while rudderless. Here you'll have to over dramatize what you would do normally, but it is still excellent practice and very empowering to learn how to manage the boat without the rudder.
For tacking try over-trimming the mainsail and under trimming the jib. Heel the boat to leeward to help it steer up into the tack. Once you pass head to wind try back-winding the jib to help the bow come through the tack. Ease the mainsail all the way to help the boat turn away from the wind on the new tack. Sit together on the windward side to heel the boat to windward thereby driving the boat to leeward. Once you are on your new heading use sails and weight to stop turning and hold your course.
For jibing try heeling to windward with the mainsail eased all the way and the jib full to pull the bow to leeward. When the boat is down wind have the crew grab the parts of the vang to pull the mainsail across. The boat may round up aggressively after this moment. Use weight and sail trim to stop turning and hold your new course.
This drill may feel clunky at first, but with practice you and your partner will get an excellent feel for how weight and sails are critical elements for steering. Once you develop that feel be sure to keep applying what you learned while bringing the rudder back into use.