1) Take break when you are stuck. When you take a break, your brain is not taking a break. It's mixing ideas around in your brain into the sub-conscious part which you are not aware of. This connects the problem with old knowledge and allows you to tap into what you already know and make connections.

Meg Selig. (April 18, 2017). "How do work breaks help your brain? 5 Surprising Answers." Psychology Today.
Thomas Carew. (January 20, 2015), "What is the best way to help my students retain information longer?" www.brainfacts.org

2) Sleep. You can't remember things unless your brain has had the chance to prune synapses and get rid of unencessary connetions so that it can grow the important ones. In order to learn knowledge or a skill well, for example to prepare for a test or perform a piece of music, you need to practice it with at least three nights of sleep inbetween for it to stick.

Maria Konnikova. (January 11, 2014). "Goodnight. Sleep Clean," The New York Times.
John Hamilton. (October 17, 2013). "Brains Sweep Themselves Clean of Toxins During Sleep."NPR All Things Considered.
Matthew Walker author of Why We Sleep https://www.youtube.com/watch?v=aXflBZXAucQ

3) Exercise is important in growing new brains cells which are produced by the hippocampus. Exercise is a great way to take a break and let your subconscious brain work.

Gretchen Reynolds. (April 30, 2014). "Want to be More Creative? Take a Walk."The New York Times.
Gretchen Reynolds. (July 16, 2020). "How Exercise May Bolster the Brain." The New York Times.
Ferris Jabr, (September 3, 2014). "Why Walking Helps Us Think."The New Yorker.

4) Make mistakes. Making mistakes in a safe place is the best way to learn.

Johns Hopkins Medicine, "Memories of errors foster faster learning," August 14, 2014, Science Daily. Yes, mistakes really do help you learn!
Benedict Carey, (September 4, 2014). "Why Flunking Exams Is Actually A Good Thing." The New York Times.

5) Don't let procrastination get you down.

Mind Tools, "The Pomodoro Technique® Staying Focused Throughout the Day."
Robert Wright, (April 21, 2012). "How to Break the Procrastination Habit"The Atlantic. (Charles Duhigg's book,The Power of Habit, which is mentioned in the article, is also great!)

MORE ADVICE

Oakley, Barbara. A Mind for Numbers: How to Excel at Math and Science (Even If You Flunked Algebra) . New York, NY: Penguin-Random House, July, 2014.
Brigid Schulte, (May 16, 2014). "For a more productive life, daydream."CNN Opinion.
Daniel J. Levitin, (August 9, 2014), "Hit the Reset Button in Your Brain," The New York Times.
Charlie Tyson, (August 14, 2014), "Failure to Replicate," Inside Higher Ed. This is a very interesting overview article about the state of affairs in education research.