Signs of a good latch

Tickle your baby’s lips with your nipple. This will help baby open their mouth wide.
Aim your nipple just above your baby’s top lip. Make sure your baby’s chin isn’t tucked into their chest.
Aim your baby’s lower lip away from the base of your nipple. Baby’s lips should be turned outward like a fish. Your baby should lead into the breast chin first and then latch onto your breast. Your baby’s tongue should be extended, and your breast should fill your baby’s mouth.
If your baby latches just on the tip of your nipple or it hurts, gently put a clean finger in your baby’s mouth to break the latch, then try again.
SIGNS OF A GOOD LATCH
Some signs of a good latch may be:
The latch is comfortable and pain free.
Your baby’s chest and stomach rest against your body, so that baby’s head is straight, not turned to the side.
Your baby’s chin touches your breast.
Your baby’s mouth opens wide around your breast, not just the nipple.
Your baby’s lips turn out.
Your baby’s tongue cups under your breast.
You hear or see swallowing.
Your baby’s ears move slightly.
If you’re having trouble getting a good latch, try:
Moving to a quiet, calm place.
Holding your baby skin to skin. While both you and your baby are undressed, hold your baby against your chest.
Letting your baby lead. Support your baby’s neck, shoulders, and hips with your hands. Offer your breast, but let your baby find your nipple on their own.
Source: WIC BREASTFEEDING SUPPORT
Link: https://wicbreastfeeding.fns.usda.gov/steps-and-signs-good-latch