Do not moisturize with only an oil - Oils apply a sealant on the skin; it does not pull in water and hydrates the skin.
Save the oil for last - Moisturizing or applying other products will not able to fully be absorbed into the skin if you apply the oil first.
Some oils clog up pores - apply on a small patch of skin so you can see what works and what doesn't. Some oils, like coconut oil, tend to clog pores easily.
Some oils contain vitamins that repair and protect - Argan oil, or example, have high levels of vitamin E and vitamin A. Rosehip oil is packed with vitamin C that protect against damage.
Certain oils treat acne - tea tree oil has anti-inflammatory properties that kills acne bacteria and reduces pimple size.
You can use oils in place of makeup remover - oils break up makeup gently instead of stripping the skin of natural oils. If you have sensitive skin, using oils can be a great replacement for irritating makeup removers.
For dry skin, try heavy oils - Although it can get greasy, oils like almond and avocado oil are occlusive oils that can help the driest skin.