If you say in your application that you are going to be an English major, at least one of your recommendations should be from an English teacher. Pick teachers who are reliable. This is also a test of your judgment. If a teacher doesn't get your recommendation in on time, you will be the one who looks bad. Pick teachers who are good writers.
Nothing is less impressive than a poorly written recommendation.
Thanking a recommender is good manners. It's also a polite way to remind a forgetful teacher to get on the stick. Send your thank-you note a week or two before the deadline.