It depends on where you want to go - there's actual k-9 training which is more involved, requires much more schooling and gets much better pay, a certified dog behavior consultant, working for a training school or owning a training school. Most dog trainers are self-educated, read a lot about training and go to seminars all over the country. There are dog training schools everywhere, but some are complete rip-offs so be very careful where you go.

I volunteered for at 4 Paws University, and dog training is a really serious job and can be scary at times. You have to be a strong person and be able to apply good judgement on the spot to solve a behavior... I don't think it's a job suited to most people, at all! But if you really want to you should totally go for it. Have you taken Sassy to Obedience classes? You should join an Obedience club, take her to classes, and volunteer to help before and after class to set up and such. You can get a lot of good advice for good trainers. Here are a couple of links ...

http://www.apdt.com/
http://www.ccpdt.org/