What do experts consider the easiest way of making a baby sleep for a long period of time?

Poor word choice : Babies will sleep continuously up to about 4 hours in one segment/day.They might come into a shallow alert state & resettle if trained to do so, like most adults(who don't remember doing so). The trick is helping baby learn to self settle by putting them down drowsy but awake to begin the night. Babies that are rocked or fed to sleep will always get up & expect help getting back down.