Make sure baby's sleeping place is safe. She should sleep on a firm surface, without blankets or quilts, pillows, or stuffed animals. (See Choosing and Using a Crib for more info below.)
Turn overhead lights off, but keep a dim lamp or nightlight on.
Create a bedtime ritual -- read her a quiet story, sing lullabies or play soft music, rock her and stroke her. Keep the routine consistent, doing the same things in the same order each time you put baby down to sleep.
If she's asleep in your arms and you'd like to put her down, make sure she's in a deep stage of sleep first. What to look for: a motionless face and limp, dangling limbs. Then, put her down as gently as you can and keep a hand on her tummy for a minute or two afterward.
Always put baby to bed on her back. Do not place her tummy-side down.
If you're going into another room, keep a baby monitor switched on, so that you'll be sure to hear when she wakes up.