Understand WHY exactly you are doing what you are doing
Plan HOW you will implement it
Ask right questions which produce right answers
Start from the basics, lowest level with 0 abstraction, no libraries, no frameworks, only you and your goal
Trust no one
Always check what you have read before following the article/advice/benchmark
Make everything maximum simple so you could explain it to 8-years old kid
Think about other developers who will read your code, imagine you are a public person and each line of your code will be judged by a million of negative comments in the social media.
Think about will your code work after 10 years without you
And always ask yourself: If you would be an enterprise customer paying a huge amount of money, would you use your own software knowing how it is written from within?