How to keep warm your baby
Babies tend to loss heat easier than adults then keeping them warm is a priority, but considering that small babies could suffocate because of blankets sucking, keeping them warm may be challenging.
Furthermore, small babies are not able to say if they feel hot or cold, so guessing how they feel is necessary to act properly, after all they will cry even if they feel hot or cold.
Certainly it's not an easy task, but with a couple of tricks you won't have troubles.
The best way to keep a baby warm is clothes layers. Begin with the diaper, over it use a short sleeves body which can be covered with a long sleeves one; afterwards a shirt and finally a sweater.
It seems a lot and certainly is, at least for an adult, but for a baby is enough, however it's not necessary to use all the layers all the time. When room temperature gets lower, add extra layers, if your baby feels comfortable, he/she will be happy and smiling, if not it won't pass longer before crying.
You may guess how your baby feels according to his/her reactions. If you add extra clothing layers and the baby is still uncomfortable (crying) probably you are overheating him/her; thus removing a lawyer or two will be enough.
When to stop? Give the baby some minutes between each clothing layer removal, according to the reaction you'll know if it's necessary to remove one additional layer or not.
Remember that what fits OK now not necessarily will do later, so you might begin with a given number of clothes layers and a couple of hours later it might be necessary to add/remove one according to room temperature changes.
On the other hand, if you are planning to go outside, especially on cold or windy days, remember to have a couple of extra jackets for the baby as well gloves and caps. Due to the size, a baby's head is a sort of "heat radiator" and most of temperatures loses are through the head, so a cap or cover for the head will be very helpful.
Blankets are not recommended at least until 12 months old due to the risk of suffocation as well sudden infant death syndrome, thus mastering the art of clothes layers is necessary to keep your baby not only warm but also safe.
At the beginning it might be hard, but with enough time you'll learn not only to know how many clothing layers your baby needs on a given situation, but also which is the reaction to hot or cold, rendering thing a lot more easier.