EDIT2: This is my take on finishing games, not about the tools/languages problem
Personally, I swear by the following two articles/pieces of advice
http://www.folklore.org/StoryView.py?story=Real_Artists_Ship.txt
http://www.defmacro.org/ramblings/taming-perfectionism.html
The latter being the most relevant in my case, because I find perfectionism and self-doubt to be the biggest obstacle to getting something done and released. The perfectionism thing can also link back to the tools problem ("Not invented here" syndrome, for example)
Of course, these aren't really "methods" as you ask for, but they are really good pieces of advice
EDIT: The other brilliant piece of advice I've seen (in a book) is from Chris Crawford. In essence, he says don't treat unfinished projects like failures - because it's negative feedback, and won't motivate you to try again. Treat them in the same way an artist does - notes, sketches, drafts
before the finished piece/masterpiece. I think that's a brilliant way to look at it, because it's true: very rarely do people leap into an idea or project and get an immediate finished product. They have prototypes, they have unfinished projects prior to it that alter how they approach its development etc.
Overall, treat it as a learning experience, not failure.
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