There are many reasons that might be causing your skin to break out. Some of the causes could be related to your hormonal changes as well as to your stress patterns.
Below are some common mistakes that can be avoided to prevent your skin from breaking out:
- Not drinking enough water:
Water helps remove toxins from the body through sweat and urine and also keeps it hydrated. In a study conducted at University of Missouri-Columbia it was found that having about 2 cups of water significantly boosted blood flow throughout the body and skin. 
- Not cleansing after travel or workout:
Not cleansing your skin after travel or workout leaves dirt accumulated on your skin, clogging pores and causing irritation. This is one of the main reasons for acne. Make sure you clean your face at least twice a day.
- Not sleeping enough:
The link may sound far-fetched but is actually quite strong. Lack of sleep increases the production of glucocorticoid hormone, which may lead to abnormalities in skin structure and function, and eventually to breakouts. So, now you know why there is so much fuss about the sleeping beauty! 
- Eating wrong foods:
No, we are not talking about oily foods, which contrary to popular belief, have almost nothing to do with skin breakouts. It is the sugary foods which inflict damage on your skin. They raise blood sugar quickly and trigger a boost in insulin that can lead to the growth of pore-clogging cells and can also hyper-activate oil glands. American Journal of Nutrition suggests that for fewer breakouts, it is helpful to add whole grains, beans, and veggies to your diet and to cut back on simple sugars. 
- Not hitting the gym often:
Studies suggest that exercise increases blood circulation, sending more oxygen to skin cells and carrying cell waste away. A word of caution! Don’t forget to shower right after a workout, as sweat from exercise can lead to breakouts by irritating your skin and clogging the pores when mixed with dirt. Make sure you maintain good hygiene – only then can you enjoy clean and healthy acne-free skin. 
 Effect of fluid intake on skin physiology: distinct differences between drinking mineral water and tap water. – PubMed – NCBI . 2015. Effect of fluid intake on skin physiology: distinct differences between drinking mineral water and tap water. – PubMed – NCBI . [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pubmed/18489334. [Accessed 21 September 2015].
 Does poor sleep quality affect skin ageing? – PubMed – NCBI . 2015. Does poor sleep quality affect skin ageing? – PubMed – NCBI . [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pubmed/25266053. [Accessed 21 September 2015].
 DIET IN DERMATOLOGY: PRESENT PERSPECTIVES. 2015. DIET IN DERMATOLOGY: PRESENT PERSPECTIVES. [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2965901/. [Accessed 21 September 2015].
 Hygiene of the skin: when is clean too clean?. 2015. Hygiene of the skin: when is clean too clean?. [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2631732/. [Accessed 21 September 2015].