This question comes up quite often in the office. My advise is to just make sure your flossing every day. Most of us know that flossing is required daily to prevent cavities from forming between the teeth, but not many people actually do what we are told. Even though flossing is a tedious process, if done regularly it can become an efficient process in your daily routine and can also help in lowering costs associated with your dental bills.
Flossing before or after brushing makes very little difference, it is truely what is the easiest for you. I personally like to floss prior to brushing as I feel it removes any food particles from between my teeth prior to brushing. This with the use of an automatic toothbrush will help decrease the amount of bacteria growth in your mouth and get you on your way to a healthy mouth.
Check this link out for further information:
http://www.mouthhealthy.org/en/az-topics/f/flossing
Remember to keep smiling with confidence