Basically the question is how to avoid landing with your skis facing across the slope rather than down it?l have just about mastered getting air and landing, but spins are a harder beast to conquer.

This requires some off slope practice. The best way to start is actually on a trampoline. Tape/pad ur skiis so the edges do not damage the trampoline.
The first step in starting twisting is maintaining correct body position. Head up & neutral, gut in, shoulders back. This position keeps the upper half of ur body strait & keeps the rotation axis even.
Now begin the twisting. Start with just a quarter of half spin jump. Keep the upper body strait by flexing the abs, shoulders back & head up & neutral. Squat slightly & twist toward ur dominate side. (This u should already know, it is merely the side u feel comfortable twisting to). Practice the small turn. You should focus on bending the knees & slightly sticking ur butt out on the landing, this ensure that u will not fall to far forward or backward as this is a centered position of landing.
You should feel comfortable landing backward as this is the first step in landing jumps. If u do not feel comfortable skiiing backward, u should also take some time to practice this. The reason for this is that not all jumps land completely turned so if u r accustomed to the feeling of going downhill backward this will save some bad crashes.
Keep building the turn progression on ground or trampoline.
Now for the slopes find a nice kicker jump that gives u ample air time without the need for a lot of speed going in to it. Work the same progression on the ground/trampoline drills but now while standing on the slopes.
Approach the jump slow & relaxed, make sure that ur r in the proper position to twist, & make a slow relaxed jump half turn. You should probably do this without poles as they r just another obstacle that u could hurt yourself on.
Make sure ur bindings r set looser than normal, if u dont know what this means, ask a pro shop to set them for a beginner skier as they r set so that the boots come out easier. This can save some bad ACL/MCL tears that could & frequently do happen.
So take ur time, u will probably not learn this overnight, but like everything practice will make this skill doable. Just remember, u can practice the wrong thing all u want, u wo not get any better. The key is to practice smart, that is where the results come from.

Hard to top that answer.but l found this site:

It is not bad.the guy who wrote it gave simple, good advice.


http://huckzone.com/tricktips.php