A friend and I were talking about mildew in the shower (we have more interesting conversations I promise) and here are some tips from the book Clean House, Clean Planet by Karen Logan:
Leave the fan on and open the window. Mildew does not like sunlight or air so turn the fan on, open the door and/or window (free show!). If that is not to your modesty liking, leave the lights and fan on after you are done showering for a bit.
Use a squeege to wipe down the walls after you shower. It only takes a few moments and makes a huge difference in the amount of mildew and soap scum build up in the shower. Mr. H does it now too-hurray! I do it before I step out of the shower and then no worries about bending over the edge of the tub with wet feet!
Use only a cloth shower curtain. Plastic ones grow mildew on them and taking them down/putting them back up for washing is a pain so just skip it. Place the cloth shower curtain in the shower when you take one, wring it out when you are done and hang on the outside of the tub, opened all the way. If you are really attached to the plastic shower curtain-cut off the bottom seam where all the yuck seems to sit and that can help too.
I also found this blog post to be chock full of information (and no bleach!)-3 Ways to Kill Mold Naturally.
Hope those tips help! If you have any to share feel free!!