If you sew you know how important a thimble is. Few things can improve quilt stitching like a good thimble. Look for one with wide deep dimples on the top. If your thimble is dimple-less you might still be able to catch a needle until you can find a better one. Make a dent in the top with a roofing nail. A few taps with a hammer or a sturdy object should do the trick. Home-made thimbles can be made from two fingertips cut off a pair of old leather gloves. Tuck the smaller one inside the larger one and start sewing.
If a thimble is to large coat the inside with several layers of nail polish. Or wrap masking tape around the inside and dust with corn starch to lessen the stickiness. Make a too-big thimble smaller by slightly tapping it on each side with a hammer.
Blow into the thimble to keep it from falling off your finger. Wetting your finger will accomplish the same thing. Glue stick on the end of your finger will keep the leather thimble from slipping. Or a small piece of Dr. Shoal's molefoam on the inside of the thimble will keep it snug.
Be careful not to hit the same spot on the thimble over and over. Try to guide the needle to a different spot of the thimbles surface to avoid wearing out one spot of your thimble, especially if you are using a silver thimble.
To prevent thimbles from rusting and staining fingers, coat them with a thin layer of nail polish.