You decide on the general Where & When.
That's the luxury of spearheading a ski vacation...it's your baby! Get a clear picture of the kind of memories you're setting out to forge and the skill level required to pull it off...lift access, self-propelled backcountry adventure, or maybe even heli-ski? Think skiing off-piste steeps, jabbing through glades and hucking powder bumps vs. cruising corduroy and kicking back in a bustling apres lounge. Pick a general mountain range or ski town and do some research into the typical weather and visitation patterns. That tiny bit of research can make a colossal difference. I'll never forget my buddy who planned his bachelor party in Whistler during Pride week...not quite the ambience he was shooting for. I've also attended a gay bachelor party during Pride time...clearly well-executed. Weather patterns may not be as cut and dry, but you can get a good sense of the general trends from looking back at previous season social media feeds. Are the Instagram posts from April still full of pow glory? (at Journeyman Lodge, that would be a heck ya!).
Define the group...would these be friends from the highschool or college era? Would it be a posse that's bonded over outdoor pursuits? Hey, some of us even like the people we work with. At any rate, pitch the idea and feel out the response. Are spouses/partners joining? This can be a bit of a double edged sword; if our mates are a natural part of the crew, the social dynamic is likely to flow with ease and the beefier head count can help snag some nice group savings. On the other hand, a not-so-familiar partner may find themselves particularly insecure among your peeps and as a result, reliably crusty and withholding. We've all experienced this dark cloud at one point or another, and its a familiar buzz-kill that's easy to avoid when simple group limits have been announced, "Sorry, muffin. We've storied this trip for ages and now we're gonna make it happen. No spouses."
Crunch the numbers. Make a plan.
How much is everyone willing to spend? Be thoughtful not to stretch that friend who's only working part-time or still paying off a massive debt. Friendships can cross financial boundaries. If some buds are hell-bent on upping the ante on 'rich' experiences, would your group consider a proportional to income approach to the the budget? Keep the budget in mind as you work out an ideal itinerary and be sure to maintain your priorities...the ski days. Reference and tally all the costs associated with your itinerary and confirm it's a go with the crew.
Take the money & Lock it in
In taking reservations I know, first hand, you should get your friends to fork it over before booking anything. It's nice to think that your peeps would be the last leave you hanging but, realistically, until that cash is in your hand...it's a recipe for friendship disaster. You're going to see way more deals if you pre-book and purchase major trip elements with a credit card; as the trip organizer, that's likely going to be your credit card (think: flights, accommodations, gear rentals, tickets). At this stage, be sure to seek out group discounts. Many tourism operators are happy to offer some sort of deal when you are bringing more than a few people to their point of commerce. Sometimes this is obvious and already laid out; usually, its in the cards if you've got the gumption to ask, "Since I'm booking this as one hefty transaction, can you offer me a better rate?". Seriously consider trip cancellation and medical insurance. Print, save, and prepare everything as it happens.
Communicate! Experiences come with expectations, be sure to manage them
Hopefully you've already read the fine print, but make sure everyone else knows about that stuff too. It's amazing how commonplace assumptions can be, and they sure have an affinity to make things awkward. Are you anticipating a scenario where gratuities might be in order? Are rentals going to be available on at the mountain or in the village? Do you have vegan bud? There's an obvious vibe when everyone's on the same page and it's up to you to ensure it's a positive one.