There are lots of different tips and techniques for how best to sterilise jars for preserves. My two preferred techniques are below.
Probably the best and most widely used method is to put the jars and lids in a low oven - approximately 130°C - for 20 minutes.
Some people say to put them on a baking sheet or to line the shelves with newspaper, but I've never had a breakage yet without doing this.
If you are following this method and using kilner jars, please note that the rubber seal should be removed before you put the jar in the oven and sterilised in boiling water instead.
Most of the time I just cheat and fill the jar and lids with boiling water just before I am ready to use them. This isn't foolproof, but I have only once had one jar of chutney go bad and I make a lot of preserves.
Don't put cold preserves into warm jars or visa versa, or the glass might crack. It's generally better for both to be warm, in terms of keeping out the bacteria.