Just think about who your users are from the perspective of your application. Is there one kind? More? Then for each kind of user, think about the big overarching things they want to accomplish. Present them those general choices, and then go from there into more appropriate interfaces for each task.
Finally, if you have a big set of steps, a wizard is nice because it lets you validate each step one at a time. This is obvious on a native app, but very handy on the web.
