Indoor putting is a great way to improve your putting stroke so long as you have a good surface to roll the ball. I would recommend purchasing an inexpensive putting mat to get you started. My favorite drill for any player is to putt using only their trail hand (right hand for right-handed golfers). Simply place your lead hand behind your back and grip the club with your trail hand in its normal position on the club. Make one handed stokes from just 3-4 feet to start. Keep your hand relaxed and just make a basic stroke allowing the club to ‘swing’ back and through. With only one hand it will be difficult to manipulate the clubhead. Almost immediately you will begin to ‘feel’ the hit and release of the putter head through impact. This releasing motion is crucial to consistent putting. After 10-12 one handed putts, use both hands focusing on the same right-hand motion. Alternate between 10 one hand strokes followed by 5 two handed strokes to solidify the feel and motion. As you gain confidence, try moving back a few more feet.
I love this drill for all levels of players. There is a reason why this has been Tiger Woods’ go to putting drill for years. And it has worked quite well for him!