I'd perhaps think about what stresses you out most - like someone else mentioned I found it more stressful to sit in a room that looked like a bomb had hit it, whilst still wearing milk splattered pyjamas at lunchtime.
For me, what kept me sane was making sure I had a shower and got dressed before DH went to work, that way if I felt I wanted to get out of the house - I could just get the pram out and go.
I also found it less stressful to get things cleared up once a day, not spending my whole time doing housework - but doing just enough.
And second time around, acknowledging this and doing something about it - rather than sitting feeling I should be spending every waking moment with my baby/not showering until lunchtime - made me feel much better.
It's the same with the whole "sleep when the baby sleeps" mantra - I find it really hard to sleep during the day, I always have done and once I accepted that second time around and just made sure I rested and ate during those times, I felt much better. Not that you shouldn't sleep or stay in your pyjamas, but do what feels right for you..
Definitely microwave meals and easy to eat food. I got lots of covent garden fresh soups to eat, which felt healthy and were easy to drink in a mug whilst feeding. Plus oatcakes and lots of bottled water with nice cordials to make them taste of something..
Also a nice shower gel ,you may not get time for a bath but at least a five minute shower with a really nice shower gel makes you feel human.
And try to get out every day, that really helped me stay sane and I think baby and you sleep better when you've had some fresh air.