How should one go about organising a skiing/snowboarding holiday for a large group of people?

I try to go skiing every year with my university, however this year I want to do something a little different.

I know a lot of people, and in turn they know some others, who want to go skiing this year. So I'm interested in arranging my own trip with lets say a group of 15-30 people.

What are the things I need to consider? What is the best time to get the bookings and such finalised? And what is the best way of going about organising this trip, both logistically and financially?

Sorry I forgot quite a lot of information that's useful. We're all UK based & British, the trip itself is likely to be the Alps or somewhere else in Europe (where ever is cheapest/best value). Budget wise I'm not really sure as I have no idea what sort of deals I can expect with group bookings, the vast majority of the group will be full time students so the cheaper the better. Again transport wise whatever is cheapest. Most of the group will need equipment hire too.