Perhaps the smartest thing you can do is keep a small piece of pure white plastic or paper with you to adjust the white balance every time you take photos. We've all seen digital photos that were taken in flourescent light that look yellow or blue, and photos taken in low light conditions around some incandescent bulbs that look yellowish or reddish. The trick here is to preset the white balance; this way the camera knows what is supposed to be white and makes the proper adjustments for color, contrast, etc.
What Dutch said about an extra card and battery is spot on. Take tons of pics, load them to your computer and figure out how to best set up the camera for your different uses.
As far a zip-loc bags, do youself one better and get an Otter box, a small dry bag or even a waterproof housing. Zip-loc bags will fail if really put to the test, I've seen it happen too many times. Lawrence Photo in Springfield has a great selection of Otter and Pelican waterproof cases.
http://www.waterproofcases.net/
http://www.otterbox.com/
http://www.casesbypelican.com/pelican-case...CFR8iIgodwU_aGA
