Taking the time to be detail-oriented encompasses the difference between acting quickly and acting intelligently.
How you can be more detail-oriented:
-- Listen before you respond -- Equivalent to "think before you act." Listen to your peers, colleagues, superiors AND competition in order to better understand a situation.
-- Review, and then review again -- Time consuming but valuable. Each time work is completed force yourself to review it from a different perspective. Textually. Graphically. As a customer. As a competitor. Etc.
-- Take notice of insignificant details -- Whatever it is that you deem insignificant now -- from word choice to colour to tone -- inflate it with importance and take notice.
-- Understand that you can be your own worst enemy -- Trying too hard, overanalyzing, and not understanding your own strengths and weaknesses will lead to your demise. Therefore, paying attention to yourself is equally as important as paying attention to what surrounds you and the work you produce.
-- Criticize -- Consciously criticize your work. Push yourself to improve (even when you think it's perfect), understand your capabilities, and incite growth. The ultimate result is you'll have taught yourself how to pay attention to details by breaking down your work into its many multi-faceted pieces and reassembling it leaving no area unscathed to harsh criticism.
Great marketing is in the details. It is those details that make gargantuan, flashy campaigns industry successes. It is those same details that can render size and resources insignificant. It's simply your job as a marketer to pay attention.