“There are three ways to manage scope creep regardless of the size of the company,” says technologist Anjuan Simmons (@Anjuan; here's his website):
Simmons recommends an agile project management practice called Scrum, which has these considerations already built into it. With this technique, the development team of designers, programmers, testers (or just you, if you’re flying solo) work in short, two-week sprints. At the end of each sprint, you should have something to deliver to the client.
“That's how you prevent scope creep,” says Simmons. “Keep the development team focused on a defined scope of work that is very valuable and can be fully developed and that can be tested in a two-week period. High performing Scrum teams can release software faster than scope can creep.”
"How IT Businesses Can Manage Scope Creep & Change Control without a Corporate Budget"