I’ve learned a couple of tricks over the years on how to upgrade to first class. The best one i know of at this point is to know when the first or business cabin is not full. I’d like our how to group to add that tip! The best way to do this is to fly in the middle of the day during the week. Most folks fly out first thing in the AM or at night because they don’t want to “lose the day.” I’ve never understood this, I guess because I tend to work in the early AM and late a night.
So, I try to take a noon flight across the country or back to LA during the week. The flight are always empty, and thus it’s easier to use your miles to get the upgrade. You of course need to have the class of ticket that can be upgraded and the miles. I’ve learned to love United’s business class (PS service between New York City/LA/San Francisco).
Also, you can ask the agent on the phone how full the first class cabin is. They are not supposed to tell you, but many times they will. If they don’t give you the exact number you can tell them why you’re asking and which flight they think would be most open and they will tell you.