Do you yell to avoid any possible collisions? Or, any other way to warn people on the trail?
1. don't go
2. keep a keen eye out and swerve when u see other ppl
keep your head up and looking around
If I am passing anybody, I just say "On your left (or right, depending on the situation)" so that they know where I am. I generally ski on the really big and steep slopes, so I am the only one there and collisions are rarely a problem.
You cannot avoid them altogether, all you can do is take precautions. Check uphill ( look over shoulder ) periodically and especially before making a wide turn. That way you can know now much space you have to manuever. For people in front of you, try to stay out of the path they are taking, yell out "pass on left/right" if you are going to be close to them.
If they are beginners and very unpredictable, find a safe time to shoot right past them. Since they won't every catch up to you, they will no longer be a threat.
Find, read and understand the Alpine Responsibility Code: