Not a new mom but new to breastfeeding


I am about to have my 3rd baby in September and I am going to try to breast feed. I didn’t breastfeed my 1st born because my milk literally did not come in, I didn’t breastfeed my 2nd because he went to nicu and then wouldn’t latch because they had him on a feeding tube then transitioned him to a bottle without really asking me. I have really high hopes to breastfeed my 3rd and final baby. She will be a c section and I’m praying so hard she doesn’t go to nicu. So with all of that, what are some MUST haves, some don’t even bother withs, and tips and tricks??? Also a question that I have, assuming all goes well and my supply comes in well, could I give the breast milk to my older kids for antibodies as I did receive the covid vaccine? 🧐