It depends on your experience. When you're starting out you want to write as much and as often as you can. Practice solving the same problems using different so

It depends on your experience. When you're starting out you want to write as much and as often as you can. Practice solving the same problems using different solutions and adding constraints. If you're an intermediate developer you need to turn to predicate calculus, logic, and formal mathematics. Learn a specification language and a theorem prover. Learn to think above the code. Learn to identify what the invariants are and then see what you can cut away from your code. Know what pre-and-post conditions must be held strongly and which can be relaxed. Etc.