Win the ball with a clean slide tackle. Recover to get level, time the slide as the attacker exposes the ball, win it with the leading foot, and get up quickly to clear or play.
The attacker drives with the ball and the defender recovers alongside, then times a slide tackle to win it as the ball is pushed too far. Emphasise getting level first, sliding through the ball with the leading foot from the side, and getting up quickly. Never dive in early or slide from behind. Rotate the roles.
Going to ground removes you from the game. That is the honest cost of a slide tackle and it should be the first thing a player is told, because everything else about when to use it follows from it. Miss, and the attacker is past you with nobody in the way. Win it but leave the ball loose, and his teammate collects it while you are getting up. Even a successful slide usually ends with possession going to somebody else.
So the situations that justify it are narrow: a ball about to be crossed or shot, a recovery run where the attacker will otherwise be through, or a last defender with no alternative. Any moment where staying on your feet and containing is still possible is a moment not to slide.
When it is justified, the technique reduces risk considerably. Recovering to get level with the attacker first is the non-negotiable, because a slide from behind is a foul regardless of contact with the ball. Coming from the side, leading with the foot nearest the ball, and playing the ball rather than through the player is what makes it clean.
Timing is the same cue as any tackle: the ball has to be exposed. Sliding at a ball still under an attacker's control is a foul with extra momentum behind it.
Getting up fast is the last coaching point and the most neglected. A defender who wins it and stays down has completed the tackle and lost the phase.
Practise on wet grass or a soft surface. Slide-tackling repetitively on a dry pitch produces hip and knee abrasions and nothing useful.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.