What are the clothes and accessories that streamline?

Summer approaches, despite the pages of newspapers and several television features I want to convince to the contrary, I already know that I cannot become a silhouette and show off a perfect line. Since you can no longer hide behind sweaters and coats in winter I wonder if there are little tricks to look thinner and hide my imperfections choosing the right clothing.

For example, it is true that dress in black and wear clothes with vertical lines? What are the clothes that I absolutely avoid? Those who grow fat and highlight the flaws?