One way to do a detox (a mild one) is to eat a step cleaner than you normally do. If you eat animal products, then going vegan is a mild detox in itself, especially if you emphasize greens, some fresh juices, and raw foods.
All raw foods would be a step beyond vegan, with all fruit being a step beyond that and a fast (juice or water) beyond that. The more 'drastic' the step you choose, the shorter your cleanse needs to be.
There are also certain foods/supplements, like chlorella, that can help with detoxing.
There are various herbal formulas for detoxing, but I like an oxygen-based cleanser called Oxypowder (www.oxypowder.com
: if you enter their monthy contest for a free bottle, you will usually get a $5 off coupon!). When I used it, my acupuncturist informed me that some acne I was getting around my nose was directly connected to the intestinal meridian and was a sign of intestinal detoxing. I also got rid of the white coating on my tongue that I'd had for a long time (maybe because I had a yeast overgrowth?).