Look at where you get your foot in the door. Being accepted by a good school or a good company might be a great opportunity. High grade employers and the best education mean you have exposure to skills and opportunities that you might not get anywhere else. Don't mistake your early career moves, no matter how good, as opportunities for name dropping. The job you get when you're first starting out can be just as important as the company you're with currently.
As a marketing professional, you need to look for places that will teach you the most and those which have the most overall application for marketing. This means, you'll go farther if you start with an entry-level position at a company primarily producing consumer products than with one that mostly works with the government, for instance. There's just more need for what you do in a company of this type. The ability to learn on the job is vital, and you'll need to get the broadest portfolio possible.
Entry level positions that provide good opportunities include brand management positions, entry level advertising jobs, and positions in web and direct marketing. However, these strategic entry points aren't all that it takes to get to the top in your marketing career. Though they can definitely help, you need to pay attention to what you're doing elsewhere as well. Make sure that you're choosing the right job and that you're developing your skills at all times, and above all, make sure that you have a plan for your career.
When it's time to make a job change, do it strategically. It's a bad idea to move laterally just to get a larger salary. You need to try to add to your skill set and round out your experience. Think about what you can get in terms of skills from the new job before you go. You need to use your skills in different contexts to keep from being pigeonholed, but you want to make sure the job you choose is right for your career. The good news is that functional thinking about your experience can let you jump across industries.
Graduate school is nearly essential for ambitious marketing professionals, too. Some say the MBA is nearly the new bachelor-level degree. That means you'll need to think about getting your graduate degree in your marketing career plan. Marketing is becoming ever more dynamic, which can be both a challenge and an opportunity, but it's one you can meet if you know what you're doing. It might not be an easy path, or one that's clearly laid out, but you can get to the top of your field. Pay attention to the opportunities that get you the greatest advantages in the long run, and your chances will improve greatly.