I'm not sure that home-grown garlic is any better than good shop-bought stuff, but growing your own gives you a nice sense of self-sufficiency.
• Garlic requires a six- to eight-week spell of cold (below 10 degrees), so - if you have free-draining and fertile soil - plant it now, in a sunny position. Don't add manure, use garden compost and a bit of wood ash (for added potash) if you have it.
• Buy from a garden centre, or seed merchant. Garlic from a supermarket or greengrocer may grow perfectly well, but then again, it may not.
• Separate the bulbs into individual cloves, discard any runts, and plant 5-10 centimetres deep (the lighter the soil, the greater the depth), 18 centimetres apart.
• If you have clay or soggy soil, plant now in modules or small pots and place in a sheltered spot outdoors. In spring, carefully transplant to open ground.
• Keep the ground free from weeds.
• In summer, when the leaves begin to go yellow, dig up the bulbs very carefully (they can be quite deep). "Cure" them by leaving in a bright, airy place (outdoors if it's dry) for a week or two.