Benefit instantly by installing the Long URL Please Firefox plugin. The plugin works in the background when every web page loads, replacing short urls with the proper ones, so that you can tell exatly where links will take you.
A picture tells a thousand words. Here's a made up, but not unrealistic bit of content you'll often see on sites like Twitter
Until you click the link, you've got no idea where it will actually take you. Will it be safe? will it be offensive? will it be obscene? will it be useful? from the url alone you'll have no idea. The context around the link will help (by who, what words etc), but quite often it's not enough to answer these questions.
Here's what you'll see after installing the firefox plugin:
Without any action, you can see that the link will take you to youtube. For me knowing this makes me more confortable, I know it'll be safe, it's unlikely to be extremely obscene or offensive and I may find it interesting or amusing, but more often I'll know not to click it since I won't take the time to watch it.
That's it - it's that simple. It's about improving your experience when dealing with short urls, by unhiding where they link to. It saves me time and frustration every day.