Fruitfulness is developed over a lifetime.
Our spiritual life is completely dependent on Jesus. This means He must prune out of our life the things that keep us from being productive and bearing fruit for Him.
Having a valuable effect on the lives of others comes from relationship with Jesus. You can't bear fruit if you are consumed with your own wants and personal happiness above the needs of others around you.
Fruitfulness comes from long term faithfulness. Strength and comfort from God's Word comes most when our time with it is a regular habit of life--not just a crisis response.
A commitment to a regular, on-going ministry position is more valuable to yourself as well as others.
More than only giving to special causes, the habit of tithing makes your whole experience of personal finance peaceful and blessed rather than anxious and worried.