The water bath canning method is definitely easier than pressure canning, so if you're a beginner, you're probably better off starting with that one.
Wash your jars and bands before use with hot water and lots of soap. You want them to be as clean as possible.
Warm the jars until ready to use, to prevent them from breaking when they come into contact with hot foods. You can do this by placing them in simmering water or a heated dishwasher.
Leave a little space between the food and the top of the jar, to allow for expansion when cooling.
Get out all the air bubbles by pushing the food against the sides of the jar with a flat kitchen utensil.
Make sure the rims are clean, and don't close the bands too tightly because some air needs to be released during the process.