DO make sure that the harness-retainer clip -- if there is one on your car seat -- is at the level of your child's armpits. If the clip is in the wrong place, the straps could slide off.
DO put an infant in a rear-facing car seat at a 45-degree angle. If it's too flat, your baby could slip down; if it's too upright, his head could flop forward and squeeze his airway. (Use a rolled-up towel under the foot of the seat if necessary.)
DO put a tightly rolled-up blanket alongside your baby's body if he's small. (Strap him in first so the straps stay taut.)
DO take your car to a local car-seat inspection site so a professional can check the installation. To find a location near you, go to seatcheck.org.
DO put your child in a booster seat when she's too heavy for her car seat, and insist she use it until she's 8 years old or 57 inches tall. A new study found that high-back boosters are safer in side-impact crashes than backless ones.
DO place the harness straps in the slots below your baby's shoulders when her seat is rear-facing.
DO make sure the harness straps are above your child's shoulders in a forward-facing seat to give her the most protection in a crash.
DO choose a car seat with a five-point harness, which will hold your child.