To be honest, I've found a good number of people that have achieved certification that can't actually do much for real. One of the best ways to learn is to pick a subject and practice it over and over, then find a new way and practice that over and over. Once you truly understand it, teach others (writing articles on sites like SSC that allow easy feedback is an excellent method) because if you can't explain it simply enough for others to understand, you don't actually know it well enough.