I'm not a professional by any means, but I have painted about 15 to 20 houses inside & out.
My best advice is to get good gear. A $12 to $18 dollar cutting brush, the right type of roller heads for the job, & switch the roller head when it stops working as good as it does after the first few rolls. Get a 5 foot piece of material like the stuff that goes on counter tops & about 12" wide to slide along the wall as a drip shield as you go. One of those 4 or 5 foot handle extensions will really help too. It keeps you from having to bend over, & gives you a longer stoke.
Take off all the face plates before you start painting, & put them into a ziplock, or in the dishwasher to clean them up. It's also a good time to buy new ones that are much nicer, & really class up your rooms look. I get mine at Wal-Mart.
I like to cut in on both top, bottom, & corners then get the roller moving fast & furious. I can do an empty house in 8 to 12 hours by myself with this method. I also use a damp rag to clean any drips off the carpet or woodwork, & I rinse it often. I like a 4 x 4 piece of linoleum to set my paint can,& tray on in the middle of the room. I simply turn the try to face me as I go.
Also don't be afraid to put the paint on thick. It will save you from doing a second coat, especially when putting a light color on a darker color.
I know you wont be working in an empty house, but use what you can. I hope this helps, & yes painting sucks!