Engage your learning skills :), challenge yourself;
Make a test with something new: take a problem on a subject you know nothing about, it’s the most difficult.
Then you find out the technique. It makes senses, and you can reproduce what you just learned.
Next step is to teach what you just learned, or write about it. How to?
Put yourself in the position you were before BEFORE you found a solution to your problem. Remember what your questions were and start from there.
IMO, by teaching a process you will become more precise and more efficient at addressing new problems. Plus, while teaching/sharing other people will ask you question you didn’t think of, and you will both improve your skills.
And practice, on new subjects all the time. Make you feel comfortable with the uncertainty of failure, the lack of ideas etc… make you feel it’s ok to do not know. Take the habit to move fast on perpectives. Allow you to move the problem the way you want to see it in different views. Don’t be shy.
Now go learn, and go solve problems!