Get your ideas out of your mind.
Most of us don’t have problems coming up with ideas. We have problems sorting, organizing, and filtering through the ideas we come up with.
The first step to decluttering your mind is writing everything down. Use a yellow legal pad, notebook, or whiteboard. You can use whatever you want, so long as it’s an analog (and not a digital) tool.
Once you’re sure you’ve emptied your mind of ideas, file them away. If you’re using a whiteboard, take a picture of your brainstorm, put it in Dropbox, and clear the whiteboard.
Now that your mind is clear, you can focus on the goals that are in front of you.