- if for some crazy reason you have a fully-refundable fare, call before the weather advisory goes into effect! You'll be able to snag exactly the seat you want before the teeming masses start calling in for their free changes.
- monitor Twitter for information about travel waivers, for better or for worse Twitter seems to be where the airlines are focusing most of their attention these days. The goal here is to get into that phone queue as soon as possible after the waiver goes out.
- if you have elite status, use the airline's elite status line to make your changes, it'll have shorter queues. If the queues are long, you can sometimes skip around them by calling one of the airline's international offices over Skype.
- while you're on hold, use Google Flights to find alternatives so you can suggest a preferred alternative when they pick up.
- be flexible. sometimes just getting there at all is more important than how you're getting there
- while there is some concept of getting a refund if you're downgraded from First Class, remember a few things: if you're on a discounted (i.e., anything that's not a fully-refundable) fare, that the fare difference is likely going to shrink very quickly as all the alternate flights fill up and the prices shoot up. Also keep in mind that during bad weather, the airlines' first duty is to get you where you're going as quickly as possible. If you want to wait an extra day or two to keep your seat in First Class you can do that, but if you choose to take a coach seat you're committing a voluntary downgrade and they don't technically owe you any money back. But if you're nice about it, you can probably get them to put you at least into Premium Economy.
- be nice to the people on the phone. I worked in a call center for years and this is spot-on. Decide before you call if you want results or if you want to yell at someone making less than minimum wage to make yourself feel better, because you don't get to do both.
- Do exactly the opposite of this if you're already in sunny Mexico and your flight home to grey and slushy New York might get canceled. We had several folks at our hotel who got told the earliest rebooking option was (gee, darn!) 6 days after their original departure date.
Some great detail about each airline's policies and contact information over at The Points Guy. Some of his weather tips are here.