The sole resource used by a writer is their mind. So, one should always try to work towards expanding the number of resources at their disposal by learning as much as they can.
Lectures, books on technique and novels written in your particular genre are all fantastic ways to help strengthen your craft. Whenever in doubt when it comes to something in your fictional story, research, research, research.
By doing as many of these as often as you can, you should be able to change and grow as a writer.