In order to text you have to be prepared. Your first step to your preparation would be to get to know your phone inside and out, practice using your phone on your free time as much as possible. When practicing with your phone you should learn where the keys are and what they do, how the vibrator operates, and how to locate you text message inbox quickly and easily. With enough practice you should be able to do these things without looking at your phone, which greatly decreases your chances of getting caught. Being prepared not only includes knowing your phone but where to conceal it when in school, baggy clothing and purses play a big part in covert texting. Most importantly make sure your phone is on vibrate upon arriving at school.
Be discrete, in order to do this, you have to be secretive about it. The first thing to consider is where you put your phone while you're texting. Another thing to consider is to not rat out your friends to the teacher that they are texting, you may think it is funny, but what comes around goes around and they might return the favor. If possible, choose a seat in the class where your dominate hand is furthest away from the teacher. The next key to being discrete is, where your eyes are looking. You might be able to text without looking at your phone, but this takes an immense amount practice. Don't stare at it (especially if you're hiding it under your desk). If the teacher is lecturing, you should either be looking at them or taking notes. Also, don't text constantly during class. You are more likely to get away with it if it's not excessive. When a teacher suspects you might be