Always be the guy in every meeting with the best design idea.That's pretty much how it worked for me. When you're sitting in a room with your colleagues and peers, discussing and debating how to solve a particular problem, and you consistently present the best ideas, the ideas that get implemented, you start to build a reputation and credibility. The next thing you know, you're The Architect. I expanded on the idea with this:
Be able to recognize and vocalize the pros and cons of every idea.Not just your own; other people's ideas as well. If you can tell them, in a polite and constructive manner, what's wrong with their idea and how it might hurt them in the near or far future, they will [if they're not a complete jackass] thank you for it, and come to you the next time they want a Sanity Check.
But how, you might ask, do you become the guy with the best ideas? Read, read, read! I am a bookworm. I read books on design patterns, frameworks, methodologies, programming languages, antipatterns, usability, etc. If you can grok it and regurgitate it at the appropriate times, you'll be The Idea Guy.
That's how it worked for me. Your mileage may vary.