The more I've learned about photography the more I've also learned that artificial filters and manipulation are often required to make a natural looking image. Slowly but surely, I've also realized that human perception and the photographic processes are quite different. Filters and photo editing programs can't replace being at the right place at the right time, but they sure can help when the lighting conditions aren't just right.
I didn't use filters for most of the photos I've taken, but there are times, like high noon, when I'll drag out the extension tube so I can screw on a polarizer filter (this is the most important type of filter in my opinion) to cut down on the glare and shadows.
Miz Donna asked me to post about another little trick I've learned by reading, and by trial and error, in a pinch you can use a pair of sunglasses (not prescription) as a filter. You use them to cut down on the glare from sunlight in your eyes, so why not lay them down in front of your camera lens (or if you have a steady hand, hold them in front of the lens) and snap your shot. I have a shot of Zach in the garden that I took through some amber colored sunglass lens but I can't find it right now so you'll just have to take my word for it, you'll love some of the effects you'll get when you try this.