The Venn Diagrams from the logical reasoning section would enhance your rational thinking skills. Take the practice test at jagranjosh.com to prepare for various entrances such as CAT, CMAT, MAT, XAT, ...
Take a look at a different problem solving exercise using Venn diagrams. Remember to draw the Venn diagram and add information as you go along. This will help you keep an overview of what is going on.