This is an old thread but I figured it'd be a good one to use for my first post.
Shooting in RAW and adjusting white balance later in PS isn't a bad idea but if you're doing it by eye and just guessing at what looks right you might be missing out. I like using a WhiBal. This gives you a true, accurate reference. And with the new keychain-sized version there's no reason to leave it at home.
All you do is take a picture with the WhiBal in the frame any time the lighting changes. So let's say it's cloudy in the morning. You take a shot of your WhiBal and fish for a couple of hours. When the clouds burn off and the sun comes out you shoot another shot of the WhiBal. When you get home to post-process you use the curves tool and with the reference images loaded you use your eyedroppers to set the highlights, shadows, and midtones. Then you can save the settings and do some batch editing. Do the same for each reference shot and use that to properly set the white balance for each group of images. It takes the guesswork out of it and helps ensure accurate results.
If you're using a DSLR I sometimes use an Expodisc. It's primarily for setting exposure it can also be used to set a custom white balance if your camera has that capability. I used that more for studio work than outdoor stuff where lighting may change several times during a shoot.