Step 1: Relax.
Step 2: Realize that everyone messes things up.
Step 3: Think positively. If you “know” you are going to mess something up, then you WILL mess something up.
Step 4: Ask for help.
Step 5: Prepare one lesson at a time.
Step 6: Realize that if you “suck” at math, then a primary school teacher is probably a good choice for teaching, rather than a middle/secondary school teacher.
Step 7: Breathe and believe you can do it.
(If you feel you will have a panic attack in front of your students, maybe teaching isn’t the right profession for you. Step back, meditate, and think critically about what you are capable of and what you want to do with your life. Once you do so, only then will you come to the conclusion of whether you are confident enough to be in front of your students, or if having a panic attack in front of the class is very likely, meaning teaching is not for you).
Good luck.
Teaching In Real Life 