Originally Posted by returnoftheyeti

Get the free no fee Chase United card to unlock the lowest fares. UA offers cash upgrades, as well as free changes, so if a better deal comes along, in any fare class, you can just switch to it.

Spend some time in the United forum to get an idea of what’s possible.

Keep your flights to 1 stop or less, don't screw around with positioning flights inside the States, and remember you are trying to fly in December where the weather is unpredictable. Avoid the east coast airports.