A note about proposals
If your proposal is not accepted, it doesn't mean it was ineffective (or bad). For the popular conferences, there is a lot of competition and they only have so many spots. Re-evaluate, ask for feedback from colleagues (or, in some cases, from the proposal reviewers themselves) and keep trying. But, again, it's not a "proposal contest" in that the best proposal wins. Reviewers consider many factors and the proposal is just a part of the programming process.
Strategies for becoming a "known quantity," which is defined as someone or something whose abilities or characteristics are well known. Being associated with a topic will increase your chances of being asked to speak at conferences and other events. It's basically about making a brand for yourself.