Convertible car seats are great for babies and toddlers because they can transition with your child as he grows. Install the seat rear-facing as long as possible. It is only safe to install your car seat forward-facing if your child is at least 2 years old or has reached the maximum height or weight capacity of the car seat. If your child meets these requirements already, invest in a forward-facing upright seat.
A 5-point harness is a combination of safety belts that clip across your toddler's chest, over his thighs, and between his legs. This harness will restrain your child in the event of an accident and keep him snug and secure at all other times.
It's also a good idea to get a seat with an overhead shield -- the padded tray-like attachment that rests in front of his belly. This tray provides extra protection in the event of a crash and is a great table for toys and other objects while traveling.
A tether is a strap that attaches the top of the car seat to an anchor in your vehicle. All new cars, minivans, and light trucks have been required to install tether anchors since September 2000, and almost all car seats come with tethers. If you have an older seat or an older car, it may be possible to purchase a tether kit from the car seat manufacturer. However, it is always best to purchase a new car seat to ensure your child's safety isn't compromised by an outdated or previously damaged chair.
Your child will have a more comfortable riding experience if she's surrounded by soft, plush pads around her head and back. If there is extra space around her and she isn't snug in the chair, tuck rolled-up blankets around her (but never under or behind) for added support.
Toddlers are messy -- there's no way around it. Save yourself from hassle and frustration by selecting a car seat with a removable, machine-washable cover. Little spills and stains aren't such a big deal when they can be thoroughly washed away.