hi, very inexperienced mum here, have 16 day old, but my advice would be SLEEP whenever you can, look after yourself (eat, drink, sleep), if baby is napping, do not use that time to do housework (except maybe putting a wash on to avoid running out of bibs/cloths! unless someone else can do that), sleep instead. i got so tired i was semi hallucinating, really not good.
Drink lots, eat plenty of fibre, fruit, veggies.
If you need painkillers & there is an alternative to codeine, take the alternative as constipation is a side effect (i mean crying on the loo, have to walk downstairs backwards, moaning, will never laugh at the word again constipation).
have a million bibs, grows & puke cloths, they go through them very very fast.
Don't be scared to tell visitors to leave.
Have lots of lovely cuddles!