How Do You Choose an Airline?

How in the world do you pick an airline for international travel when you’ve only internationally traveled once? The only time I had been abroad before last summer was for a high school senior trip. Everything was taken care of by the school, tour company, and my lovely parents. Fast forward 12 years, and I had no idea what airline I should book for my upcoming summer travels. There are dozens of airlines. Which one to choose? Being an elementary school teacher, my main criterion was easy- the most budget-friendly. I was just trying to get from point A to point B in one piece and preferably on time. I think those are pretty reasonable expectations.