How to breastfeed
BMJ Group Medical Reference
If you've got mastitis, you've probably been breastfeeding for at least a few weeks. But it can be worth going over the basics. Some health professionals believe that mastitis happens because of poor breastfeeding technique. Although there’s no evidence that this is the case, it can help to know you’re doing it right. Here we describe what position you and your baby need to be in, and the signs that tell you that your baby is feeding properly.
The first thing you need to do is get into a comfortable position. Make sure you’re sitting down with enough room to stretch your arms out to the elbows. Use cushions if you need extra back support. Remember you’ll be in this position a lot, maybe for a long time.
Once you’re comfortable you need to get your baby in a good position for feeding:
Hold your baby close to you with their body facing yours
Your baby’s head and body should be in a straight line
Make sure your baby’s arm does not get in the way (it can go behind you)
Keep your baby’s head and neck well supported but leave enough room to tilt their head back
Hold your baby so their nose is level with your nipple and close enough to get a big mouthful of breast
Keep your baby’s nose free for breathing (do not push it into your breast)
You may find it helps to hold your breast from underneath, by making a C-shape with your thumb and forefinger.
The next thing you need to do is to get your baby to latch onto your breast. Your baby may do this without you having to do anything. But if your baby seems reluctant then you may need to encourage them. Try teasing your baby’s lips with the nipple to get them to open their mouth.  As your baby opens their mouth, push your breast towards it with your nipple facing towards the roof of their mouth. If your baby does not want to feed, then stop and try again later.
When your baby is properly attached you should notice the following: 
Your baby’s mouth is wide open
You can see the coloured skin around the nipple: you should see more of this above your baby’s mouth and less underneath their chin
Your baby’s chin is touching your breast
Your baby’s lower lip is rolled down
Your baby’s nose is free.
It's normal to feel some discomfort when you start to breastfeed. Your nipples may be sore and your breasts may feel very heavy and full, especially when your milk first comes in. This usually happens about three days after you give birth. But you shouldn't be in a lot of pain. If you are, ask a health professional about it.
There are certain signs that will tell you that your baby is feeding properly:  
You should be able to hear and see your baby swallowing
Your baby should have a rhythmic suck
Your baby’s arms and hands should be relaxed
Your baby’s mouth should be moist
Your baby should have regular soaked and heavy nappies
Your breast should feel softer as you feed
Breastfeeding your baby should make you feel relaxed and even sleepy.
For references related to Mastitis click here