Blackberry bushes are often defined by their large thorns, which can be several inches long as well as sharp. Take care when picking the berries, because the thorns can scratch and prick your hands.
Plant your blackberry bushes along the perimeter of your yard or garden plot. The less contact you have with the bushes, the less likely you'll be to get pricked by the thorns. If you're planting several bushes, keep them far enough apart so that there's enough space around each one for you to pick the blackberries while minimizing your chances of getting pricked.
Wear a long sleeved shirt to protect your arms from the sharp thorns. Long thick pants, such as blue jeans, would also be beneficial. If you have gloves that allow for easy gripping and movement, they'd come in handy as well.