From my point of view I'd say build a foundation for your game with the tools you already know.
(In my case that would be writing the story prior to creating the world with the help of other tools)
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When I venture into unknown territory I'm often met with frustration and demotivation as long as the challenge is higher than my skill level in that field.
Regarding the schedule I'd take John Cleese advice on creativity; set out a time and place to do the creative work. This means that you need to find an "oasis" where you will be left undisturbed for a period of time. Set a strict time interval for the work, about 2 hours in the beginning, where you will do nothing else but this creative work. Remember that you have to calm down in order to enter the creative state. It's simple in theory - but I've found that last part most crucial.
Things that I have found true which might relate to this:
* Inaction breeds doubt and fear.
* Follow your interest and you'll find yourself in interesting situations with interesting people - who find you interesting.
* Improve the situation instead of improving your mood. Progress will elevate your mood. Don't let days fly by because you are waiting for that moment when you feel "motivated"
* Work with other people - unless you're introverted.
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