You may already be following your friends, family, business associates and peers on Twitter. Now it's time to add some of the most popular Twitterers to your account to see what they're up to. Popular users run the gamut from celebrities to stock tips, limited-time deals from commercial tweeters to news bites from well-known journalists. follow Oprah on Twitter, follow Ashton Kutcher on Twitter and see what the other half is saying.

There are so many services that keep you connected with friends, family and associates that it can be hard to keep track of them all. Fear not! Twitter allows you to post Twitter tweets to Facebook, MySpace, Blogger, TypePad and other online services. In part two of our Advanced Twitter Tips series, we'll show you how.

We all make mistakes. Sometimes, you choose a username for an online service that is now either embarrassing or downright lame. We're looking at you hockeyguy523. You too, lovetheladies141. Fortunately, with Twitter, there's an easy way to change your username without losing your followers or disturbing your Twitter stream. Here's how to change your Twitter username.

It doesn't take long to reach Twitter feed overload. Once you start following tens, hundreds or even thousands of people, it can be impossible to keep up and important tweets might get lost in the shuffle. Here's how to subscribe to a Twitterer's RSS feed so you never miss an important tweet.

On Twitter, as in life, good manners will get you far. Unspoken Twitter etiquette dictates that you not share the mind-numbing minute of your day. However, otherwise boring tweets can be made useful and valuable, which is the most important step in getting followers on Twitter. We'll show you how.

Finding hot topics and adding your two-cents is easy on Twitter. In this installment of Advanced Twitter Tips, we'll look into how to search for and chime in on hot Twitter topics. Everything from the newest gadget, the finest recipes, the latest sports discussions and much more are happening right now on Twitter!

With tens, probably hundreds of thousands of tweets being sent every day, there's a lot of raw data for to search through if you're looking to find a specific topic. Twitter, apparently, agrees and so has a robust advanced search engine you can use to drill down and find just the info you're looking for.

If a picture is worth 1,000 words, then pictures have never been more useful than they are on Twitter, with its 140-character posting limit. Molly McDonald demonstrates how to share a picture with your Twitter network using TwitPic, Flickr or Photobucket. In fact, if you're already on Twitter, you don't even need to sign up for TwitPic; you have a login!

Sharing links on Twitter is all well and good, but how do you know who's visiting the links you post? Bit.ly is a great service that shortens URLs, just like TinyURL does, but with the added benefit of letting you see who's clicking on your links, when, how often and even if they're sharing them!

Twitter's popularity has grown to the point that celebrities are jumping aboard the bandwagon. Everyone from US President Barack Obama to Ashton Kutcher, Britney Spears to Shaquille O'Neal, Jimmy Fallon, Demi Moore, Arnold Schwarzenegger (or, in some cases their team) and more are sharing their thoughts.

You've followed our Beginner's Guide to Twitter and you're regularly updating your followers on what you're up to. Now it's time for some more

advanced Twitter tips

. In this series, Molly McDonald covers everything from posting pics with your tweets, finding celebrities on Twitter, using the advanced search capabilities of Twitter and even changing your Twitter username.