1. Block off specific times to study and prepare in as much in-advance as possible.
Do not take the exam on a whim, thinking your experience will carry you through the exam or that you will get used to the questions. This is how people fail on their first try and need to fork out another $200 for the exam. It took me about 1 week of "fake studying", not really retaining the information and about 3 weeks of serious studying and reviewing the EPA Certification Study Guide to get the material down at about 1 hr a day. I would answer each of the questions after each Type and sub Type and if I could not repeat it in my head, I would go back to study the material to commit it to memory. I also wrote down all the dates and numbers on cheat sheet to get them straight in my head. Ask someone to quiz you if it helps. Also sometimes, writing the answers out by hand or creating flashcards can help commit them to memory.
Many EPA Certification testing centers are conveniently at your local HVAC supply store, which do not require prior reservations. It is always a good idea to call before hand though and let them know when you are planning to take your exam. If your exam is at an EPA approved testing come prepared with a pencil, non-graphing calculator and personal identification. Scratch paper will be supplied by the EPA Universal testing center.
3. The day before the exam
Get plenty of sleep before the EPA exam so you are well rested. Review any notes or cheat sheets you have made yourself. It's definitely possible to learn new material the night before, but you should have been doing it in some kind of structure and on the last leg of your study material.
4. The day of the exam
Eat a good breakfast and get well hydrated. The prime times to take exams are mid-to-early morning. During the EPA exam, take small breaks if you need to.
Getting your EPA certification can open plenty of opportunities for you and definitely work the effort. It can never be taken away and unlike other certifications you do not need continuing education to keep your EPA Certification card.