got my confirmation number from united airlines, leaving march 12 next week, what elese needs to be done to get on the darn plane?

Are you going to Mexico?

a passport if going to Mexico

Make sure you have a seat assignment. The night before travel, you can go online and check in. Saves a few minutes at the counter. Make sure you don't CARRY ON any liquid of any kind, over 3 ounces or TSA will keep it!

I'm going to make baggies of protein powder for the ride home and maybe some packets of Crystal Light to carry with

This is what I wish I had taken, extra PJs and extra underwear (I forgot my underwear) and footie socks/slippers and flip flops. You probably will go shopping, but at soon as you get back to your room, you will want to put on comfortable clothes ie PJs. I flew United also and they allow you to check one bag for free, I HIGHLY recommend doing that. When I flew home, I upgraded to 1st class at check-in. It was the best $75 I have ever spent.

Also take broth packets with you, the food and drink taste different in Mexico, except the bottle Water. I bought juice and yogurt from Walmart and it was NASTY!!