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"Prototypes are a designer's best friend" - Instead of trying to implement everything immediately, an iterative design process involving multiple partially functional prototypes helps isolate specific issues, and gets many of the big things out of the way by the time you want to focus on details. The benefits of prototyping vastly outweigh the costs (if you are reasonable about how you go about it).
"Vast changes may be the easiest direction" - Getting too attached to an idea can bog you down. If too many users take issue with something, even if it's a big component of your design, it may be best to scrap it and try something completely different. This is related to users always being right, but just because a design idea is important to you, it isn't necessarily a good idea for you to keep.