One good way that I found is to lower the scope of the project and set clear goals and milestones. If you look at a project as a whole it might seem massive and too much to comprehend and it might be a bit off-putting. I made a checklist which I have accessible and constantly look at to track my progress... Another important this is to get people involved early. Like friends, family, co-workers. Let them try your game at early stages to get you feedback. It's a great boost to see when they enjoy it, and when you get constructive feedback. Impress them Even if your game is quite simple you will be amazed by the energy you get from... "Wow, you made that???", and people will constantly ask you. "How's your game going?".
Another good thing is to write down somewhere what you imagine your end result to be like. Collect a scrapbook of screenshots from other games that you like, that might inspire you. As soon as you have a clear goal, break it down to smaller pieces. My milestone lists look something like this.
1. Create basic controls and movement of the character. (Very important the get the feeling of how the game will behave)
2. Create player & enemy sprites. (Now you can start killing something)
3. Create Enemy AI.
4. Create UI.
5. Create scenery for 1 complete level. (Now you will start to see what the game will finally look like, even if some sprites are still placeholders)
At that point you are well on your way, and you should have a solid working prototype so start planning for your next milestones.
Each part can be broken down to smaller pieces to make it even more easy. For example:
1a. Create walkcycle.
1b. create idle animation
1c. Create jump animation.
Once you get the ball rolling and you see the game taking shape step by step, it's very rewarding. Especially when you present the next version to your group of test subjects.
Anyway. That works for me. Some things might be too hard to do so I scrap those parts, rethink my approach or learn as I go by making a new small test project only for that part.
Just go for it. Hope it helps.