I'm probably going to repeat some of what's been said by pp's but here is all the advice I can think of (sorry if it's long):
Read up beforehand so you know what to expect. Things like cluster feeding, stuff that could affect the frequency of their feeding like growth spurts and teething. The best resources I found were Kellymom, Analytical Armadillo and MN. For most issues, like if your supply is low or whatever, the solution is to feed, feed and feed some more!
I was latching incorrectly at first - I was holding the baby's head too far away because I was scared of her not being able to breathe! Luckily a midwife spotted this and told me not to be afraid to hold her really close to my breast. I'd have saved myself a lot of pain and blood if I'd done this from the start and I'm very glad she noticed at the check up!
Hopefully, everyone around you will be supportive but in my case my dp's family were totally against breastfeeding. So I would say just be prepared that you could get some negative comments. I found either reciting the WHO guidelines or smiling, nodding and ignoring whatever they said, worked best for me. But aside from them I got no negativity and I hope you don't either.
It can take you and the baby a while to get used to latching correctly etc. I also lacked confidence to feed outside the house to start with. To help, I used one of those cover things at first. Once we'd both got the hang of it and I'd breastfed outdoors with the cover a few times I soon felt confident enough to stop using it and started feeding her without. A lot of cafes will happily give you a quiet corner if they have one and you ask, if you feel you need one that is. But most people really don't even notice.
Breastfeeding made me incredibly thirsty to start with so I got in the habit of carrying a water bottle everywhere I went, at home and out. One with a sports cap is good as it's less likely to spill. And snacks you can eat with one hand, like cereal bars are handy to have too.
And very importantly, don't be hard on yourself if it doesn't work out for you. I'm sorry you felt guilty for not being able to breastfeed your first child. Do your best, if it happens it happens, if it doesn't, that's what formula is for.