Beating Hard Songs in the Guitar Hero Series

The three most important aspects of Guitar Hero are Gold Stars, Optimal Star Power Paths and Squeezing

If you can Gold Star (Hit 100% of the notes) a song, try doing it without adding any extra strums. If you can do this, study what sections of songs give out star power phrases and design a path to get the maximum multiplier from it. This will give you killer high scores. To take your score even higher, try squeezing. Squeezing is when you time the activation of star power so that it occurs at the same time of hitting a note slightly later than supposed to. Then, you hit the last few notes of star power as early as possible, trying to get one or two notes under star power that you normally wouldn't have - if done correctly.

There are some songs that are extremely difficult to Gold Star. They are:

Texas Flood (GH1)*
Cowboys From Hell (GH1) *
Bark At the Moon (GH1) *
PsychoBilly Freakout (GH2)
Hanger 18 (GH2)
Freebird (GH2)
Beast and the Harlot (GH2)
Trogdor (GH2)
Six (GH2)
Institutionalized (GH2)
Jordan (GH2)
Electric Eye (GH: 80s)
Play With Me (GH:80s)
Because, It's Midnite (GH:80s)
Ballroom Blitz (GH:80s)
Before I forget (GH3)
Stricken (GH3)
Raining Blood (GH3)
One (GH3)
The Way it Ends (GH3)
Through the Fire and Flames (GH3)

*achieving 100% in Guitar Hero 1 does not award you with golden stars.

Some songs are so difficult to Gold Star, that it hasn't been documented to be done by anybody (as of January 28th, 2008):

Bark At the Moon
Ballroom Blitz
One
Through the Fire and Flames

ii. Two Handed Tapping

In order to get some crazy songs, you have to resort to another tactic - the Two Hand Tap. Some songs move so fast that it's either impossible or highly unlikely to be able to hit all of the notes with one hand alone. Fortunately, these notes are typically Hammerons and Pulloffs, so you can release your hand from the strum bar just long enough to play the frets using fingers from your other hand. This takes practice to become accustomed to, but once you get it, several songs that appeared to be impossible become relatively easy to do.

Unless stated otherwise, these songs are all found on Guitar Hero Two. Songs that two handed tapping makes easy:

You Really Got Me
Arterial Black
Through the Fire and Flames (GH3)
YYZ

Songs that are fun to two hand tap, although not necessary:

Thunderhorse
Six

Songs that are impossible without tapping:

Jordan
Because, It's Midnite (GH:80's)
Raining Blood (GH3)
Hanger 18

Well, those are the tips. I hope you find them useful.