1) What program are you using?
Mac:
Use Final Cut
PC:
Linux:
One of the times that you really would want to use Windows. Dual booting is really nice for stuff like this.
Windows:
Use Sony Vegas

2) Make sure your default browser is Firefox.
Search the addons and get a youtube video downloader. Get the one with the most votes/downloads.

From there you can snag any video you want to edit.
As long as you don't upload them on any sites you're pretty much guarnteed not to get in any trouble.

3) Edit to Dubstep
I like doing it just because if I take my time, they look SWEET at the end.

What I'm saying:
Find a song like cinema by Skrillex. Basically any one that has a sweet drop off.
Then find any footage you want, and edit it to fit the song.
When I do this I usually think about the audio and go record some shots to fit.
It requires a lot of precise editing, and in the end you have a SWEET video you can show your friends.

Do a few of those with some special effects, and you will be a lot better than you were before.
Note: Don't throw in too many special effects/the wrong special effects. It's really easy to over due it, and it just looks ugly. (Use them, but don't overuse them.)
Also, if you want to upload your video afterwards on youtube, it's a lot more accepted now than it used to be. While you will not be able to earn youtube partner off of other peoples content, most record companies have started to allow use of their songs in others videos. They either make money by having an ad placed on your video, or having links to buy their song below the video.

--
If you work on any videos and you want me to review it / help you with it (so long as you're using Vegas) just send me a message here on TTG. I'm more than happy to help Putting myself in your shoes I know I would appreciate it.

Cheers
-Dave