To be honest, I wouldn't bother painting and retiling unless it is really bad. A freshen up to cover any scuffs or marks, yes, but don't redo the whole thing.
What's the first thing you're going to do in your new house? Redecorate!
Do make sure it's clean and tidy. I wouldn't object to clean washing drying, but I do object to food crumbs all over the place, cobwebs and a bath that looks like a peat bog. If your house is dirty, I will suspect there are also bigger maintenance issues.
If you have a dog, do shut it outside when there are viewings. Just because you love him, doesn't mean I'm not wary of him or want him to slobber all over my shoes.
Do make sure you open the windows and that the house smells fresh. Ask a brutally honest friend to do a smell test. A musty smell is also likely to make me suspect maintenance issues.
Do make sure the agent is briefed (or you are ready to explain) about any quirky things - unusual bathroom arrangements, when the heating was installed, that sort of thing.
Don't sit in the house and glower at me while I'm viewing if the agent is escorting the viewing. Go out for half an hour.
Don't cook fish/curry/anything really noxious the night before a viewing.
Don't obsess about the house looking like a show home. The buyer has got to be convinced that they can live it in from a practical perspective.
Best of luck!