A question comes in about how to effectively use a mirror during the offseason and inside to help his game.
You can practice multiple things for your swing inside. Most notably and importantly are your path or swing plane and your club face position.

Checking and working on your plane. Mark a spot on the floor where you will satnd eacha nd every time. Take your 7 iron and and get in your address position. Have someone take a dry erase marker and trace your golf club shaft in the mirror or you might want to use a piece of tape. Now make slow motion back swing rehearssals tracing the line or tape going back. This will help you learn to swing the club more up the plane on your backswing.

Position at the top and club face. Rehears your backswings and check and make sure that your left wrist is flat and that your club face is square (45 degree angle) at the top.

All done very slow speeds and I prefer with a weighted club.

This actually can put you ahead of where you thought you would be because without the ball you can do perfect repetitions each and every time!