Product Designer with an eye for detail based in London, UK
Whenever possible let users have control over customization of the product and service. Design it to be easy to execute (as breaking an egg) and to have a high perceived contribution (as cooking a whole cake).
“The details are not the details; they make the design.”
Having inconsistent interface is like trying to communicate with the user in several languages. Only the advanced users will be able to finish their tasks. Keep it simple and consistent.