When a lot of players try to serve faster, then end up "arming" their serve...

And while you might get a little more oomph, often your first-serve percentage nosedives...

The secret to serving faster AND staying consistent is to use your lower body to generate more serve power...

That way your shoulder and arm can stay loose and relaxed so you don't end up with this tradeoff of more power but less consistency.

Today I've got a really simple drill that shows you how to do that: