ISSA, NSCA are good ones to choose from. But Like what BioAs said, get ready for the bull from the public. You will be very sucessful as a trainer if you have lots of energy, look skinny, and u tell 'em it is ok to have cookies and pizza in moderation,lol. I could not stoop that low. It was very difficult for me to train your average Joe because I was a little more blunt, and the public wanted to hear the other things. However, I did have good success with the guys and gals that wanted to achieve their results no matter the sacrifice.
This one trainer that I am personal friends with got ACE certified and he is dumber than a box of rocks. He said the test was multiple choice. He would ask me to write his clients' programs for him, I never did. One day I was in their working out and he had this young girl on the decline bench doing decline ab crunches. It was so funny because every time she crunched up to the top they both yelled out "ABs by spring BReak". I started rolling and I asked him what the hell he was thinking when he did that, he told me that they were going to do crunches every day for 2 weeks so she would have abs by then. He was motivating her. LOL He was so freakin stupid. LOL
Good luck with everything.
