Game development certainly has unique challenges when compared to other fields of study. However, the basic key methods for success are common for any project. The first key is to start with small manageable pieces. Take a large task and break it down. It is much less daunting to get quick wins than try to tackle a mammoth-sized task. There’s a waterfall effect as you finish piece after piece. There’s a momentum that builds as you begin to see the progress. This will keep you motivated as you move forward.
How about an example? Here’s an example. You can’t start with “I want to make Flappy Bird, but you have a missile launcher, and powerups!” It makes sense to break it up. You might start with drawing the bird player image on the screen, then add in some basic movement. Once that looks and feels like you want it, perhaps you move on to drawing a moving background. Once that feels right, you can add all of the other crazy ideas you have — one piece at a time.