Local economies in countries that receive economic immigration and the country of origin of this flux of migration obey the contexts and dynamics that can be put in perspective to create synergies and to operate to the development of these same migrant populations. The informal economy generally presents an abundant offer in sources (type of distribution and types of actors) and is rich in the diversity of references (in products and services) but it confronts itself to a volatile demand or more precisely a random “willing to pay”. The latter justifies itself by the economic environment characterized among other things by a weak consumer purchasing power and a household confidence that does not aim for the purchasing of pleasures but to those dictated by the strict necessity and the weak occurrence of purchasing based on stimuli where the vector is the publicity or the visual presentation of the sample. In these conditions, building an informal business and succeeding is a challenge that star ts with the assimilation of the basic entrepreneurial notions before secondly dwelling on the levers to improve sales, notably by the mastering of the newest declensions of marketing (an adequate promotion of the quality and performance) more adapted to realities of ethnic or informal entrepreneurship and therefore of the community economy. We go towards a rehabilitation of the consumer taken into inertia by the “fear of unemployment” (dead Time) engendering the debt and of the producer taken into attraction by “the comfortable price” (without effort) engendering speculation. This passes by the modeling and later the explanation of the economic mechanisms in play. Then by the invitation to a change in attitude. This guide is nothing but the star t of this process.