Learn to deliver value not code. Code is expensive to maintain and deliver. You should create as little as possible to get to your end goal. Keep all your code

Learn to deliver value not code. Code is expensive to maintain and deliver. You should create as little as possible to get to your end goal. Keep all your code as human readable as possible. If there are business rules related to your code make sure the comments explain the business rules. Learn SQL, it's an amazingly powerful tool. Becoming very good at creating complex queries is very valuable. Keep it simple, complex solution are only good when a simple one wouldn't fit.