An Online Presence Doesn't Just Happen
Having 500 and then 1,000 and then 10,000 fans on facebook or any other social network is not something that just happens, unless you already have this many loyal supporters offline. It takes a little more effort than just picking a username.
1. Have A Website
Have you ever been to a band or company Facebook Page and searched for their website address for more information only to find that they don't have one? Yup, that's disappointing so make sure you don't put your supporters in the same boat. Create a website for yourself or your band that is reflective of your brand.
This site will be your online home where fans of all kinds as well as potential fans will be able to come and go as they please. What it should contain is everything they need to know about you. Make it a one stop shop. Your history or bio should be their as well as a way to contact you or your representation. If you have CD's available online, make sure they can purchase them from your site. Anything you want people to know should be there.
2. Decide Which Social Network(s) You Like Best
Figuring out what social networks you want to use is the second step to starting your online presence. The most important things to consider during this step is to figure out where your fans already are and decide what networks you like and will be able to manage. You should be able to go to this network several times per week uploading content and engaging with your supporters.
Make every place where you have your information or are represented online reflect you. Customize everything to fit what you want it to look like. Don't just go with the default network settings. Make sure people know it's you. Add your logo or your face to your profile avatar's and banners. There should be no question as to if your facebook or your twitter is really yours. This is especially important on twitter since most of the time if a twitter account still has the default egg, you can bet it is a fake or robot profile and you don't want your fans mistaking you for a robot. Plus they will likely want to be greeted by your lovely face when they check out what new thing you've posted! Have fun with this step and make it yours!
4. Say Hey!
Just putting up videos and quotes and stuff is not everything you should be doing. Stop and say hey to your followers, they are on your profiles and website for you so have a dialog. Don't get so caught up in putting out content that you forget to engage with them.