To be preparation before the effects of the variables external that influences in the supply of the product, its production, like the incidence of the state with its actions, the one of the competition, the one that the same globalisation has generated. Like also that described so well, used is functions that are expected of the department of markets, what so preparation this its resources human. The certain thing, that it is necessary, to avoid a series of errors that can seriously be given and be affected the waited for performance of the function of markets. On the matter of it, in an interesting writing on the subject, it contributes to us Alexander Juregui, that definitively there are many errors comment when he is not understood clearly the importance and the impact of the policies of trade of the companies. A flat vision of the businesses and thoughts of short term, often have destroyed good ideas of businesses, by a total disconnection between the company and its system of marketing. It proposes the suggestion of not committing some errors that are indicated and that of them we will pause in two, who we considered important Between the errors that indicate are: To compare the market with the sales? Not to constantly think about the system of attention the client? To forget that a client frequents is more valuable long term than an occasional sale of high entrance. To put major emphasis in the volume of clients and not in its quality and yield? to base the determination of the prices on the highest cost instead of an objective price? To separately plan the tools of communication and without integration with the trade system? To sell the product, without including/understanding and to respond to the real needs of the consumers Of the mentioned ones is important detenercese in the reach than it represents for example, neglecting as it happens in many of the Venezuelan companies, especially its SMEs the related thing to put major emphasis in the volume of clients and not in its quality and yield. .