In order to properly secure the car seat straps on your child, first you want to make sure that they are at the correct level. So for rear facing car seat you want to make sure that the straps are coming out of the car seat at or below the shoulder level. So when it's rear facing it kind of comes up above the shoulder and down up against the body. For a foreword facing car seat it's the opposite. You want o make sure that the car seat straps come out of the car seat at or above the shoulder level as there is a little bit of wiggle room right here. After you've made sure that the proper level, they can be re threaded. Some of them allow you to adjust them easily without re threading the straps just depends on your car seat. Then you make sure you buckle all of the buckles on the correct places. So at the crotch strap if there is any loose wiggle room, most car seats will have multiple holes where you can have that crotch strap come up through the car seat. So choose the one that is closes to your child's body but not uncomfortable. If you can't find the perfect fit you can always take a receiving blanket or a small towel and wrap it upside, inside their little crotch, next to the crotch strap to get a little bit extra cushion right there. Then you want to buckle the chest clip. Chest clip should always be at the armpit level on the child right on top of their heart cage. Because in an accident you don't want it to be in their soft tummy tissues on top of their internal organs you want to make sure they've got right up against that tough bones to protect their body. The last thing to check is that the tightness is proper. There is usually a string, a strap at the bottom of the car seat where you can pull and tighten the car seat and you shouldn't be able to pinch the strap on that strap. If you can pinch it it's too loose so a lot of parents make the mistake thinking Oh, the baby is uncomfortable, it's too tight, they are crying . If you start them from a young age and you always have them snug and secure on their body they will get used to it and it's much much safer for the child. Some people also use the 2 finger test if you can fit 2 fingers underneath the strap it's too loose. So I really recommend you don't put any bulky jackets or large winter clothing underneath those straps. You want them to be right above the onesie or the baby's clothes so that in an accident there is no extra cushioning that they have to get through to get to those straps and they are very snug and secure and safe in an accident.