The consulting industry is a very competitive field with an abundance of highly educated professionals with proven track records of success. In order to succeed and stay relevant in such a competitive field, consultants have to keep their knowledge up to date and continuously hone their skills. The question is, what is the best way to develop skills and grow professionally without the big price tags that come with graduate and postgraduate courses. We've asked top consultants to weigh in with their favorite tips for skill development at zero cost.