the Virtue to See
It is a virtue to see things, and without this virtue it is improbable to capture affective frames.
Of course advertisement is an entirely different arena of the photography industry; however if you are one those photographers crawling the streets, you definitely need to teach yourself to see what's in front of you. The best shots usually are those that you have not put any extra efforts other than actively witnessing your environment.
Most of the time, things happen in front of you while you are stressing yourself to find something worth to photograph. However, looking at things are not the same as seeing them and seeing is a difficult task to accomplish. You need to train yourself to clear your mind from the day's stres, and you need to train yourself not to rush things but to take your time. Once you calm down, and clear your mind, then you are good to go.