Guitar Hero: Metallica

I found that if you played Bass on Bob Seger- Turn the Page, you can do it, the song isn't that hard to do on Hard, there are only a few orange notes, and as long as you have a basic grasp of how to play a song on Medium, ie being able to hit all 4 of the other notes, you should be able to get this no problem.

Fairly self explanatory and easy. If you're having trouble try Bass on Hard, its very very easy.

Also, if you look at the video below, it's the second song (The Unforgiven) on Expert Bass. This was a sightread.

This one was simple, and doesn't take much. If you have some control of your voice, plug in that old Rockband microphone and start the career on hard. You can simply take the first song "For whom the bell tolls". Try not to fall asleep through the long intro, but the song is fairly easy. Hint: You don't have to sing the words, the game wouldn't understand it. Just hum the correct notes and keep your voice matched. Without trying much, I easily made it through on hard. This also unlocked the "Motorbreath" achievement for completing a song as a singer as well.