Improve your baby's sleep?
No precipitation

Baby almost does not assimilate the cycles of night and day during its first four months. Some mothers are luckier than others, but it is rather a happy coincidence that their baby prefers to sleep at night and not the day. You do not have to and will not be able to force your baby to spend his nights during his very first months, however you can combine the conditions most favorable to his falling asleep.
I adapt to my baby

I do not stress about her sleep and try not to stress your baby too much with sleep and sleep at night. Your baby feels all the stresses and tensions, be zen and patient, your baby will necessarily feel it positively.
Give her some guidelines

Help your baby better spot the time of night and sleep. On the evening arrival, use soft lights (or lower the dimmers) and lower the sound level (TV, music, conversations). Avoid stimulating it before sleeping. On the other hand, in the morning, bring more light into his room and share the sounds of the awakening of the house.
Do not cry as soon as he cries

This is the most difficult part. Try to resist the urge to come and see him as soon as he cries. From week to week, try to delay the moment when you go to see it (having however checked before going to bed that it is not thirsty, too hot, or needs to be changed). From 4 months, try to let him cry for long minutes (it's hard but it's almost a must).
Offer it a good environment

Avoid baby PVC pillows that unnecessarily perspire babies and disrupt their sleep, prefer the bags that breathe. Choose him a good mattress (new and if possible allowing the air to circulate well). Always prefer a sleeping bag rather than a blanket, so baby does not uncover at night. Install a soft, subdued light in her room. Do not heat your room too much, baby sleeps better in a cool room.