Hi Trin, we haven't spoken before but I've followed you for a while (in a nice non-stalkerish way.)
I can be a terrible slattern and I really have NO excuses, so if you are trying hard then so will I.
I think the worst things to get on top of you if you are not very careful are laundry, kitchen mess and paperwork.
So: Try every day to do one load of laundry. I've learnt that if I am very disciplined about drying and folding each load promptly, it becomes much less creased and therefore less likely to need ironing, which takes care of another awful job.
Don't leave your big kitchen clear-up to the very end of the day, or you'll get tired and won't do it. But make sure you do at least ONE good kitchen clear-up a day, pref. early evening.
Paperwork. Even if you don't action it immediately TRY to makes sure you put everything that you KNOW needs your attention in one neat pile, somewhere where things won't get lost, or forgotten. That way it's less stressful when you are prodded to deal with it but can't even find it!
For yourself I think it's really important that you get washed and dressed and brush your hair, and go outdoors for a little while each day, even if it's just to buy a paper, walk for 15 minutes in the park, anything, and TALK to people, anyone, smile and say good morning to strangers, don't avoid eye contact with people you know, because you feel too wretched. (Don't know if you do this, but I'm guessing - from experience when I was a bit depressed I would avoid having to chat to even my good friends.)
Good luck.