I took the CELTA.
I would say, be prepared to listen, and get a separate binder for all the handouts they give you. Pay attention to how they want the reports, etc. filed. There's papers for you, and papers for them. Figure out which is which.
It will be very intensive. Period. It makes people crazy. If you are taking it at an ESL institution, try to get access to their magazine clippings, etc. Get on the internet and print other resources as needed. (You'll know what you need when they tell you.) Manage your time obsessively, get enough sleep, eat right, and get as much help as is reasonable from your instructors. It's not like a school test where you study and sit the exam. They want to teach you and assess how you respond and apply their teaching.
*Watch your language grading closely- speak clearly and don't use complicated vocabulary and grammar structures with lower level students.
*Find ways to reduce the time that you, the teacher, are talking, and give the students activities to work on together instead. "Student-centered" is the magic word. TTT= teacher talking time = bad news.
They will probably start out by telling you what to teach, and giving possible materials.
You can do it. They don't want to fail you. Best wishes. It's a highly appreciated certification.
- For Teachers