Choosing a car seat and using it correctly can be one of the most overwhelming and confusing parts of early parenthood. The sheer amount of information out there is daunting, and your child's safety rides on it - literally. This guide is NOT meant to be complete or exhaustive - ever-changing standards and new seats coming out constantly would make that near impossible; this is just to get you started.
Each type of seat has 3 recommendations: one budget-friendly option, one with a few more bells and whistles, and one that would be more of a luxury. There are many, MANY more car seats out there, but this is meant to be a less overwhelming list. Both Babies R Us and Buy Buy Baby allow you to test floor models in your vehicle, and it's a great idea to check fit and ease of installation before purchasing when you can.
Rear-facing only seats are frequently the first types of seats that parents choose. Generally, they are used from birth until approximately one year old, at which point babies may move into a convertible seat. These seats are usually used with bases that they easily click into and out of, and - as the name implies - they are ONLY used rear facing.
Convertible seats are built to be used both rear-facing and forward-facing. Some parents choose to skip the rear-facing only seat and use a convertible from birth. As long as the seat's harness fits correctly, there is no safety risk in doing so.
Here's where it gets a bit confusing. Combination seats are forward-facing only. They have harnesses, which can then be removed to become a booster. Not everyone will need a combination seat - depending on the size of your child and how long-lasting your convertible seat is, many parents can go straight from a convertible to a booster.
Boosters are seats that help keep the seatbelt positioned properly. There is no harness function. Used correctly, there is no inherent safety difference between high-back and no-back boosters, although the high back boosters do provide a bit more support.
Read. The. Manual. No, seriously. Read the manual - for both your seat AND your vehicle. Not only does the manual give you valuable information about how to use and install your seat safely, but if you live in one of the 48 proper use states it's actually law to follow your manufacturer's instructions. HINT: Your manual will tell you NOT to use aftermarket accessories like toys or "cute" covers, not to strap harnesses over bulky coats, and it will prohibit using a car seat atop a shopping cart. The manual will show you correct chest clip placement (ahem, it's called a CHEST clip) and how to tighten the harness to pass the pinch test (you should not be able to pinch any slack in the webbing at the shoulder). Your manual will tell you when your seat expires - Yes, car seats expire. No, it's not a marketing gimmick.
Use best practices. The child passenger laws vary across the 50 states AND change every once in a while. If you are following best practices, you will not need to worry as the laws in most states advocate for very minimal requirements. Following best practices will not only ensure that you are within the legal guidelines regardless of where you travel, but it is also the safest for your child. Best practices advocate that your child remain rear-facing until *at least* 2 years old and until they reach the limits of their seat - as close to 4 as possible. It is further recommended that children remain in a harness until they are booster ready; not only should they be large enough to meet the requirements of the seat, but they also need to be mature enough to sit properly *all the time,* including while sleeping or on long trips - most children will not meet this milestone until at least 5 years old. Finally, children should use a booster until they have passed the 5-step test to fitting a seat belt correctly. For some children, that may be until 12 years old!
Register your seat. Your seat will come with a postcard to register it with the manufacturer. Fill that in and mail it! If the manufacturer makes a guideline change that retroactively effects your usage, they will let you know. If there is a recall for all or part of your seat, they will contact you. There is no reason not to take a moment and send your registration in.
but don't stop there. Certified Child Passenger Safety Technicians are valuable community resources, but we are not infallible. We are human, after all! The sheer number of available seat/vehicle combinations means it is *impossible* for any one person to keep up with all of the quirks. At a busy car seat check event, the tech may not have time to read your manual for you and find out any exceptions your particular seat may have to common usage guidelines. Certain seats, for example allow overhang, while others require the entire base be firmly on the vehicle seat. Some manufacturers prohibit the use of pool noodles or towels, while others rely on them to achieve correct installation. Each seat has details specific to itself that a CPST might not be aware of; READ YOUR MANUAL.