Guitar Hero: Warriors of Rock

Quite an easy achievement if you have some patience. Especially if your on bass or guitar playing on beginner. But if for whatever reason you cant play the guitar/bass/drums on beginner (or if you just do not want to play the song all together) use a mic. Just plug the mic or headset in and play on beginner in Dominate Quest mode. All you gotta do is blow into the mic when the notes come up or if your really lazy (like me) put it up by a fan.
You will be able to get the majority of songs done this way but just keep in mind that this method will not work for every song in the game because some songs have little to no vocal parts in them. For these just plug in any other instrument on any difficulty and try to achieve the full 40 stars that you need. Just note that some songs will be almost impossible to do this via this method.

Important Notes:
To unlock Dominate Quest mode you have to get the demigod of rocks guitar. (Unlock everybody's true rock form)
Another thing to keep in mind is that if your going to grind out the majority of the songs this way, it will become significantly harder to get the Gem Hoarder achievement. (Hitting a cumulative total of 150,000 notes in Quest mode) Credit to Kaisar Villhelm for bringing this to my attention

Tips:
If you have Star Power Tap on and have the mic by a fan the star power will normally come on as soon as you get it. To turn this on just start up a song like normal and hit start-go down to options-make sure star power tap is checked. (If Star Power is not coming on for whatever reason you can turn it on by the A, B, X, or Y buttons.)
Star Power is a big factor for getting 40 stars as well so make sure you or some other source is activating it. (Thanks to Wdog999)

Comment if I missed anything...plus if your gonna thumbs down me at least comment on why and I'll fix it :)

All you have to do for this is complete quest on any difficulty, so do it on a difficulty you're comfortable with. Eventually you have to 40star all the songs in quest (known as dominating chapters).
The songs are easy, the only songs people may have trouble with is the "Demigod Of Rock's gig". It has all the hard songs such as "Black Widow Of La Porte" by John 5 and "Fury Of The Storm" by Dragon Force. If you are not an experienced player then practice the songs.