Being fast is good but playing smart on the bases takes the cake! Check out the great info included here to make your baserunning more productive. Give the opposing team fits by being smart and aggressive on the bases. It doesn't just come naturally. Like all aspects of softball, study and practice play key roles in improving.
Here is an excellent article on Baserunning Basics by Coach Krause. Come back here after reading his write-up to get some good tips on Stealing bases.
Below are a couple helpful videos on Stealing. Each gives fantastic insight to help you Steal more bases.
Stealing Video 1
Stealing Video 2