Drain a little slow at first and recirculate the wort to get the grain bed set up before you add any sparge water.
Don't dump the recirculated wort or sparge water in. Don't add the water at the walls of the mash tun. And keeping the 1" of water over the grain will go a long way to preventing it.
Ideally you want to sprinkle it over the surface. That can be done with a fancy sparge arm, or I have found pouring the water into a colander set on top breaks it up nicely You can, if you keep an inch or so of water above the grain, sort of ladle it by submerging whatever you are scooping sparge water water with into the water and allowing it to flow out gently.