The more knowledge you have, the more your opinion will be sought. Become an expert in topics relevant to your company, introduce yourself to upcoming technologies, and also know what is going on in your own company.
People who get shit done are the most important to a company. I've seen whole teams paralyzed by differences of opinion, and all it took was one person to create a adequate solution. Sometimes taking the initiative means doing grunge work, like setting up the bug tracking system, or continuous integration server. Help people out, including those outside of your own immediate team -- it gives you visibility and garners reciprocity.
Communication is the most important skill IMO. I noticed a general correlation between people's position in the company and their ability to communicate effectively. It is the topic I could write the most about, but I will relate just the few important things.
* Learn to listen, and understand what people are saying tells you about their point of view and assumptions. Most disagreements IME are because people's underlying goals and assumptions are different, and a lot of times participants are unaware of it. They may be arguing apples and oranges, but think they are talking plums (If that makes sense?). Bring those things into alignment first, and building consensus will be much easier. Lastly, ask questions to resolve ambiguity, and test for false closure.
* Vocalize your thoughts concisely and understandably. Someone who rambles and doesn't get to a point, often gets interrupted or ignored. Also, as silly as it sounds, speak loudly, carefully, with conviction.
* Learn to write well. Aside from correct grammar and spelling, it means conveying information efficiently and understandably. Long gobs of text [like this diatribe ;)] often cause people to lose interest.
* Lastly, gather a bag of communication tricks. These can be general strategies for say building consensus in an unruly team meeting, or starting out a discussion with "Let me tell you the problem I'm trying to solve, and you can fix my thinking."
Well, that's my two cents worth. Feel free to message me if you have more questions.