Looking after yourself
It is important to eat well, making sure you eat from all of the 5 food groups. In order for your body to produce milk you will use an extra 600 calories per day. Eating well and being healthy means that you are giving your body the best chance to breastfeed successfully.
It is also beneficial to ensure you drink water. Recommended water intake is 2+ litres per day for regular people, you might find this is enough for you. I would usually suggest to drink to 'thirst,' no need to over do it, but definitely don't under do it! Avoid alcohol and limit caffeine intake to 3 cups per day.
It is also very important to try to get sufficient rest when baby is sleeping. Take advantage of all those offers of help from well meaning friends and family. If they want to come and visit you and the baby, instead of bringing a gift or flowers, maybe they could bring a preprepared meal for you and your family? Or do some ironing/washing. Ask your partner/husband to take the baby for a walk so you can have a quick nap or an uninterrupted cup of tea! Or settle them after a feed so you can get back into bed quicker. Often dad's are better at settling as baby cannot smell the breastmilk from you.
Lastly, make time for you. Take the time to enjoy a nice relaxing bath, go to the gym, an invigorating walk on your own or with a neighbour/friend or even a massage. These short breaks from the stress of parenthood or breastfeeding can mean you are better equipped emotionally and physically to handle to stress of parenthood.