I started doing this and will never stop! My tub shower are always spotless-so simple. Simple shower and tub cleaner: fill wand half and half. Wet surface and scrub. wow! leave in shower wash while you are already in there - This SO needs to be done in our bathroom.
use candle wax before spray painting to give that worn look
Getting out grease stains. I always use Dawn dishwashing soap. If the grease stain is still there after washing and drying, you'll need to "reactivate" the grease stain by spraying it with WD 40 (sounds counter intuitive, right?), then putting Dawn soap on it, let it sit for a few minutes, rub the spot with an old toothbrush and then wash. Comes right out!