Promoting managers from within the ranks of your sales staff can be an enticing prospect. After all, your best salespeople, presumably, have proved to be trustworthy and hardworking—and they already know the ins and outs of your operation.But promoting from within is not without its potential pitfalls, say retail experts. Not the least of which is the possibility that other staff members may feel resentful about being overlooked, or jealous of their recently advanced colleague. And new leaders are required to move from working shoulder-to-shoulder with their teammates to supervising them—which comes with its own set of challenges.Sales trainer Carlos Quintero, founder of Sales Effectiveness Inc., says the benefits of promoting employees from within are numerous, including the fact that they’re already familiar with the working habits and personalities of the store’s staffers. But