Before getting started, ask yourself a few questions to establish where you stand.
What do you need to complete this? Do you have everything ready to go?
What does success look like? How will it affect the world when complete?
Can this be completed? Criteria can change, don't forget to evaluate if a project still makes sense to do (or is even possible to complete).
Don't break your project into a giant checklist.
This will just overwhelm you and discourage you from getting started. Instead, try to think of this large project as a collection of smaller projects that build toward the same ultimate goal.
Break the project up into phases. For smaller projects there may only be two to three phases. Large projects may have five or six.
Create a checklist from your first phase. This is where we'll get started.
If you start to get overwhelmed, check to see if your phase is too large. If so, split it into two phases and focus only on the first one.
Once you've completed a phase, review your setup questions, and move onto the next phase.
What does success look like for this project and how can you measure it? You should track a project to ensure that success was achieved, and learn from any potential mistakes.
Don't just let projects fade without learning from them.
That's half the fun.