This article from Mashable.com offers some great tips for networking and building your online audience, and I've added some of my own twists for journalists.
1. Find the authors of the content you read. Follow the people you want to be like. Engage with them through their social media by thoughtfully commenting on their posts and adding to the conversation. Help them to notice you, and their followers will start to pay attention to you. Your favorite writer's audience can become yours too.
2. Write. Build up content. No one will want to stay on your website if you look like you're brand new. If someone goes to your page, make sure they will feel engaged and have a lot to read. Before you promote your work too much online, make sure you have enough of it to show so you look credible.
3. Leverage twitter keyword searches. Search for topics related to your area of journalism. Engage in conversations and allow people to get to know you.
4. Join relevant LinkedIn groups. Type in a topic you're interested in, and you can find dozens of related groups. You can start or add to conversations on the group pages. This is a great professional networking environment.
5. Meet the people who are looking at you. On LinkedIn, you can set it so you can see who has recently looked at your profile. Build professional relationships with these people because they are clearly interested in you.
We can go far by networking with successful people online.