Unless you have endless amount of air to shush your baby to sleep with every stir...get a sound machine! White noise mimics the womb environment to help babies settle.
As part of your bedtime routine, place the sound machine in the nursery (not too close to the crib) and turn the volume on low. Your sleep will forever change when fussy babies get a gentle reminder that they are not alone- they are in a sea of peaceful whales singing, nature chirping, or another soothing setting.