Like any mission-based game, like GTA or Call of Duty, you will gain points by beating levels or sections of the main campaign of Brutal Legend. These will be achieved through natural progression of the game.
Got a Car and a Date – 15 pts - Completed "Welcome to the Age of Metal."
Start a Revolution – 15 pts - Completed "Exploited in the Bowels of Hell."
Thick as a Baby's Arm – 15 pts - Completed "Lair of the Metal Queen."
Hair Remover – 15 pts - Completed "Battle for Bladehenge."
French Kiss Instructor – 15 pts - Completed "Pilgrimage of Screams."
Chicks n' Booze n' Stuff – 15 pts - Completed "Sanctuary of Sin."
Ran to the Hills – 15 pts - Completed "It's Raining Death."
Fistfull of Fog – 15 pts - Completed "Dry Ice, Wet Graves."
No More Tears – 15 pts - Completed "Sea of Black Tears."
The following achievements involve defeating the campaign on varying levels of difficulty. To save time, skip the easy campaign. If you beat the campaign on normal, you'll get credit for beating in on easy, same goes for completing the game on brutal - you'll get credit for beating the game on all difficulty levels. Be patient on Brutal, it is a very aptly-named difficulty.
Groupie – 25 pts - Completed Campaign mode on easy.
Roadie – 25 pts - Completed Campaign mode on normal.
Legend – 25 pts - Completed Campaign mode on brutal.