I've found this article about design mistake and I really want to show with everyone: I expecially agree with unskippable cutscene.. worst mistaks (IMHO, of course).
Design a game is difficult point and using my experience as professional developer (not for videogames), many many times I found myself with common problems: time schedule, lack of scheduling, demotivated people or simply no coordination.
Use my experience in videogame programming (and design of course) is important, with many differences: no bosses, no excuses, no every-day-time devote to videogame programming. So decide a rule, or better a shedule is a key point.
My advise is to write down everything, in a excel-like file: every single and atomic task you want to perform on your games, divide it into subtasks and put a category on all of them. In few minutes I have a schedule for my games, but also I have all core design concepts in one place. So it's easy to "think before do (tm)" and more important to avoid design mistakes.