Three Tips for a better start:
Pull the block with your arms. In the above video you can see Kelsi Worrell using her arms to get her body off the block more quickly and in a lower position. The arms should pull your front knee down slightly towards the pool before swinging forward into a streamline.
Kick your back heel up. First the back leg kicks up and then the front leg rises to meet the back leg. This is critical to putting your body in a negative sloped position that will maximize speed transfer as you enter the water.
Hold your line until your toes submerge. Sometimes swimmers try to angle towards the surface too soon and lose their line, this often looks like legs slapping the water and creates a large splash and displaces a large hole in the surface. Don’t change your line until your toes are underwater.
In the video you can see Kelsi Worrel utilizing all of these strategies to her advantage.
Try a butterfly start to generate more momentum. The circular path that the arms travel through during a butterfly start allows for energy to transfer more efficiently and allows for a faster and more powerful start.