Each manufacturer has its own unique set of ingredients, but a few commonalities hold true across brands. Most moisturizers will have a set of organic oils that act to seal in moisture [source: Evans]. They ensure your skin won't dry out over the course of a day, and they'll help protect it from harmful outside irritants.
You'll also likely find shea butter, glycerin, silicone, aloe, omega fatty acids, antioxidants and a form of sunblock. Each one serves a specific purpose but won't harm you if you don't have the skin type specifically targeted. Aloe and antioxidants are the main ingredients found in nearly all moisturizers. They're important for keeping your skin healthy [source: Nazario].
But don't just look for what you need -- keep an eye out for those ingredients you want to avoid. If you're prone to acne, stay away from moisturizers that have mineral oil, lanolin or waxes -- or, at least, avoid using them on your face. A better bet would be to purchase a noncomedogenic moisturizer (a moisturizer that has been tested on people who suffer from breakouts) [source: Skin Care Guide].
Alternately, if you suffer from itchy or dry skin, steer clear of acids -- specifically alpha-hydroxy, glycolic and salicylic acids. They're beneficial for people with acne or oily skin, but they'll be harmful for those who have dry skin [source: Nazario]. That's because acids have a drying effect.
Regardless of your skin type, perfumes and preservatives can be irritants. You can roll the dice and give them a try but understand that it's a risk [source: Mayo Clinic].
You can find lots more information about moisturizers and skin care on the next page.