Find your support system before you encounter problems - whether r that's an Internet forum, breastfeeding support group, national helpline, or a helpful SIL who's been there before :) maybe include links to helpful websites (MN, kellymom, drugs in breastmilk info) and the helpline numbers as well as locations and times of local groups if you know them.
The more you feed the more you make. Empty breasts make milk faster, full breasts make milk slower. Boobs don't need time to refill. You always make milk on demand even if your breasts feel soft and deflated.
It's normal to experience a supply dip at around 3 months as this is your milk changing from hormone based to demand based supply. Some women get a gradual change and some experience a sharp difference but it's okay and not to worry about.
It doesn't have to be all or nothing. If you decide to give a bottle evert now and again it's not an issue. Do what works for you. Supply can be regained. Do be aware of how supply and demand works and that your baby will want more milk when they are building up for a growth sport and your body is built to respond. So to protect breastfeeding keep bottles either consistent (using breast for fluctuating or changeable feed patterns) or just infrequent.
Not all hcps are trained in breastfeeding knowledge. Double check advice.
Pain in the beginning - 10 10 rule. Count to 10 seconds or 10 sucks and pain should subside, if it doesn't, seek help. This initial pain should last no longer than about 10 days, if you're still getting in tial pain on latching after this and it's not improving seek help. Pain isn't inevitable and you don't have to push through it. Lansinoh, free boob time, breastmilk can all help bleeding nipples heal.
I'm sure you'll ret loads of suggestions on here but I'd encourge you to keep the list short - 5 most useful points perhaps with directions on where to find further info. Anything longer makes bf feel scary and difficult to get right and you won't want to scan through all of it in a crisis.