What is the easiest way to use flux when you are soldering?

As a practitioner in the field of electronics and soldering, I'm often faced with the challenge of efficiently utilizing flux to ensure a smooth and reliable solder joint. Could you elaborate on the easiest way to apply flux during the soldering process? Are there specific techniques or tools that you recommend to ensure even distribution and prevent excessive or insufficient application? Additionally, how do you recommend storing and maintaining flux to ensure its effectiveness over time? I'm particularly interested in strategies that minimize waste and maximize efficiency.