#1 Use Antibiotic Soap
Antibiotic soap helps to clear up and prevent the infections caused by ingrown hairs. There are a number you can purchase on-line or at the drugstore, two are PanOxyl (with 10% hydrogen peroxide) and Reviva (which makes a whole line of hydrogen peroxide products).
#2 Exfoliate, But Be Gentle
Exfoliation with a wash cloth or a loofah can be a great way to get rid of dead skin cell, and can help prevent ingrown hairs. However, if you already have a number of ingrown hairs (especially if they are infected) clean them up before you begin exfoliating. Otherwise, you may further irritate your skin and make your condition worse.
#3 Moisturize, Moisturize, Moisturize
Since hard, bristly hairs more easily penetrate the skin than soft hairs, make sure you use a lotion to keep skin and hairs soft. Moisturizer is also good for providing a barrier against the outside world, whether it is clothing (legs, pubic area) or the face (beards, scruff).
For the legs, I like lotion with tea tree oil (which is a natural antiseptic). If you are adding your own to your lotion, don't use more than two or three drops at a time, as tea tree oil can be very drying. Tea tree can now be found at a number of drugstores now, or you can look for it on-line at Amazon (there's several sizes you can buy, click here) or at any store selling essential oils.
For the men, the only beard/scrubble lotion I know is made by Bluebeards Original. It is made to soften bristles and help prevent ingrown hairs (this is what my husband uses, you can get it online or at some natural food stores).
#4. If Your Condition Doesn't Improve, See a Doctor
As always, see an expert if your condition does not improve or worsens. Doctors can evaluate your individual needs and prescribe medication, if necessary.