To ease your baby into nap time:

Set the mood. A dark, quiet room can help babies sleep.
Put babies to bed drowsy but awake. Babies sleep best when they're drowsy. Before babies get too tired or cranky, try singing soft lullabies or swaddling or massaging them. In time, babies learn that these activities mean it's time to rest.
Be safe. Put babies to sleep on their backs. Clear the crib or bassinet of blankets, stuffed toys and other soft items.
Stick to a schedule. Babies get the most out of daytime naps if they take them at the same time each day and for about the same length of time. That doesn't always happen, of course. But babies with good sleep routines are likely to adjust to schedule changes as they happen.