Expressing is a bitch and not as effective as actually feeding, so can affect supply. People might suggest expressing "to give you a break" but it was harder for me. I had to express instead of feed anyway, it was easier to just feed. Those night feeds are really important to trigger hormones and supply. Plus by the time your dh has got up, messed around making a bottle while baby is screaming, you'll be awake and could have fed and been back to sleep far quicker.
My top tips would be:
Don't weigh. Go on clinical signs (wee, poo, hydration, crying, sleeping, just instinct really) instead.
Just feed on demand. Ignore any "helpful" unsolicited advice and other people's opinions, just feed.
Get your dh to help out by doing housework, cooking, shopping, taking the baby for a walk while you shower etc. you just sit on the sofa with snacks and TV and feed.
Co sleeping up to you. It is easier but you have to be comfortable with it. Dummy from about 6 weeks if you feel it's neccesary.
Like pp said, it's a full time job and really take determination, stubbornness and focus. I found I had to fight against quite a lot of well meaning people who thought it was too much for me, or how did I know I had enough milk, or my milk wasn't good enough (when they weren't sleeping 7-7 or going 4 hours between feeds at 12 weeks), or a million other reasons why I should give up. I got good at saying, no she's fine, I'm fine, it's working well, there's no reason to stop.