a) figure out why you want to do the degree. this is where the vast majority of people who say they want to do an mfe fail. if you don't know why you're applying for this, you won't make a convincing application and you won't be convincing in interviews, so better to not waste your time and money.
b) figure out what job you would like to do, keeping in mind what job best suits your skillset.
c) start with the multiple guides andy has posted here. they are by no means exhaustive, but they are pretty comprehensive. go to the programs that are listed and see if the curriculum will help you get where you want to go and whether the program's placement can get you where you want to go. look for employer names, titles, etc., job placement and internship numbers.
d) if you find a few programs that you like, check their average scores and other information against yours. are you a good fit?
e) whittle it down to a handful of schools.
f) apply.
edit: a digression... the above steps should be obvious, but they aren't for most people new to this website. i wonder why that is.