Prepare for berry-picking by wearing protective clothing such as close-toed shoes or boots, long sleeves and long pants to protect your skin from thorns and insect bites.
Pick only ripe blackberries because unripe berries don't ripen after picking. Instead, leave unripe berries on the bush to ripen for wildlife or other pickers Ripe wild mountain blackberries are not large but they are plump and deep in color. They are easily pulled from the plant and don't require any effort. The ripest berries are often located in the center of the bush.
Drop blackberries into a shallow, lightweight plastic bowl, basket or bucket. Don't compress the berries, because the fragile fruit is easily crushed. If you are picking with your family or a group of people, be sure everybody has his own bucket.
Move the blackberries out of sunlight and into shade to keep them from deteriorating. Place the berries in a picnic cooler or refrigerator as soon as possible. Fresh berries keep a few days, and sometimes as long as one week.