Choose Garlic by weight. The heavier it is, the fresher it is likely to be. Large heads have bigger cloves that take longer to dry out.
The more garlic is cooked, the milder it gets. Roasting produces a mild, sweeter, nuttier flavor; boiling a mild flavor; sautéing, a moderately strong flavor with more bite than boiled but less intense than raw.
Garlic sautéed with onion will almost always burn. To avoid burning, add garlic at the end.
Fresh garlic does not burn as quickly as older garlic because it has more moisture.
If garlic is old, remove the green germ center in the middle of each clove, age makes garlic bitter.
Keep garlic in a cool dry place in a net bag or garlic keeper (a covered ventilated ceramic dish).
Chop garlic at the last minute, as soon as it is chopped it begins to loose its characteristic pungency.
To keep garlic from sticking to your knife, chop with a little salt or fresh herbs.