The simplest way to link Facebook and Twitter is to use the Twitter application (or app) on Facebook. While on Facebook, use the search bar to find the app simply titled "Twitter." From the app page, click "Sign in with Twitter," and it will ask you to plug in your Twitter sign-in information (or it might automatically detect your account if you're already signed in with Twitter). The next page will let you know that your accounts are connected. Make sure to click the box under "App permissions" that allows Twitter to post updates to your Facebook profile. And, voila! Your tweets should now automatically show up on your Facebook profile. Administrators of Facebook fan pages can also take advantage of this application.
But the Twitter app won't carry over certain tweets, like @replies. If you want more control over what kinds of tweets carry over, try the "Smart Tweets" app. This app will give you the option to include or not include @replies, @mentions, retweets and #hashtags.
But perhaps you don't want too many tweets to carry over to Facebook. Maybe you're a prolific Twitter user who only wants a few of your tweets to post on your Facebook profile. To do that, you may want to use the "Selective Tweet Status" app on Facebook. This is also simple to use. When you sign up, your tweets will only carry over to Facebook if you end them with the "#fb" hashtag.
There are still more programs that you can use to link your Twitter and Facebook accounts. You can even use Twitterfeed, for example, to reverse the direction these other applications take and post your Facebook status updates to Twitter, but this is slightly more complicated to configure [source: Messieh].
In the end, whichever method you choose ideally should fit your needs and streamline your social network updates, saving you time and effort.