I hike in the rain if I am caught in it. If I have a trip planned, and it looks like it is going to be a washout I will try to reschedule it for another weekend. I still probably get rained on roughly 50% of the time though. The last year or two with the droughts in the SE have been a little drier.

Some other posters gave some good tips on clothing so I won't go into detail on that. I typically use Marmot precip stuff if it is cold (<50 deg), and a sil-nylon poncho when it is warm (>50 deg). If it is really warm then I just get wet and dry out in camp.

One thing not mentioned in any of the other posts is stream crossings. Depending on where you are hiking and if you have stream crossings, then you should take that into consideration. I had to turn back once when I was hiking in Slickrock Creek (NC) due to Slickrock creek being so high from an all day rain. I also had a real interesting hike out on the Forney Creek trail in the Smokys (NC) after a long hard rain. On that trip it started raining during the night, and never stopped the whole next day. I decided to hang out under the tarp in the morning to see if it would let up. That lead to leaving camp late and having to ford Forney Creek several times when it was much higher than normal. Had I left earlier the crossings would have been easier as I was watching the creek rise while sitting under the tarp. By the time I got to the crossings the "creek" looked more like class 4 rapids in the Colorado River.

So anyway, I now have a "cutoff" time. If it doesn't stop raining by 10:00 in the morning I am packing up and heading out.