Breastfeeding help

Carolina
So I'm having my third baby in July and I REALLY want to exclusively breastfeed. I tried with first two , but it was a horrible experience, my nipples would burn from the pain , I couldn't get the babies to latch on properly , I felt like they weren't getting any milk, and one of my nipples doesn't really "poke" out ..Etc etc, any tips or things I can buy to make this successful this time around??? Thanks girls