Plenty of great advice above.
I use fox bags, tied with Korda tape. I tend to use them only if I'm unsure of the debris or weed on the bottom though.
If you know it's clear just use pva stocking, it's much quicker, less mess, easier to cast & goes straight on the hook, so if you miss your spot, you can put another one on in seconds. I protect the hook point with a pva nugget.