The fourth step is determining your style. (Mostly from tvtropes)
[Original Flavor]: Are you sticking as closely to the tone and mood of the original work as possible?
[Darker and Edgier]: Or are you taking a decidedly more cynical look at the world? Showing the seedy underbelly of a happy fairytale kingdom? Or, if the work is aimed at children, simply the POV of an adult and adjusting the world accordingly? Now, be careful. There's a difference between taking an honestly deeper and more cynical version of the world and characters, and just ramping up the violence and bringing sexy back where it wasn't wanted in the first place.
[Lighter and Fluffier]: Or are you going to give your favorite characters a break from all their angst? More humor, a gentler look at life, and solutions to problems abound. See also WAFF (acronym: Warm And Fuzzy Feelings.) This might be charming and delightful, but it is in as much danger of pitfalls as Darker and Edgier.
[Earn Your Happy Ending]: Or, heck, are you doing a little of both? Fights are harder, the risk of death is real, all of the conflicts are more gray or technicolor, and yet the moment of glory is just that much sweeter for it all? Of course, there's also the risk of Mood Whiplash and Mood Dissonance tossing the reader right out of the story if it isn't done well, just like by making it darker or lighter.
[New Flavor]: Something that does not fit a set criterion, changes as the story goes by, or is "unstable" in a sense. Not recommended.
[Mixed Flavor]: A story with various styles depending on the environment and its changes, and also characters.
(Reminder: More than one cannon relation, genre, and style can coexist in a single work).