Oily skin generally has a shiny or greasy appearance with uneven skin tone and is prone to blackheads and breakouts. Just having a bit of a shine is very often more a sign of combination skin. Oily skin is caused by over excretion by the sebaceous glands. This may be brought on by hormonal changes, such as in the menopause or pregnancy - but if you just have over-active glands then so be it. That said, oily skin may be made mopre noticeable due to stress and tiredness, pollution and of course, an unhealthy diet. Using the correct products, here, is essential.