Take care where you cool your jars. I once ruined a vanity by using it as a cool-down spot - even with layered towels as a cushion, the heat from the jars made rings in the wood. I also agree that removing the rings is a good idea (it can be a place for mold to grow) and to also wash-down your jars after they have cooled. In addition to removing any odd bits of produce or sticky juice, it will also alert you to any jars that don't have a full seal. Label your finished product with at least the year canned and what is inside - I can't remember how many times I've grabbed a jar of jam with absolutely no clue when it was put up...or if it's the pure raspberry or the raspberry-strawberry. Experiment with adding flavors to jams - vanilla for a sweet touch, chocolate for richness, jalapeno for a bite, ginger for a snap. A little goes a long way.