Keep instruction simple and short. If you cannot demonstrate properly show video or have a skills athlete demonstrate it. Ensure maximum practice time and repetition of skill. Make drills that allow everyone to practice skill. Avoid all drills that have athletes standing around.
Games are tests also.
Training devices such as spike trainer, batting tee, etc. can be useful. Auditory aids can also be used. Practice Design well planned practices that get maximum activity by all participants. Short practices are usually better for younger players, mastery of a new skill, and high intensity sports. Longer practices may be productive for players who are in good condition, endurance sports, already learned skills, and when interest levels permit.