#1
I am stuck, I am trying to write a really good melody on guitar but it just ain't happening. I can write riffs easily but I can't seem to write a good melody. I am trying for something like the main part of Knights Of Cydonia by Muse. Any suggestions?
#2
Lots of people start with a chord progression and find a melody that fits it, although Paul McCartney does it the other way around (or he used to). It may help to understand how notes resolve to each other, how they fit the chord progression etc.

Play a scale, melodies tend to start and finish on chord tones, usually the 1 and 5.
Non-chord tones create tension that wants to be resolved by playing a strong chord tone straight after.
Play the 2, does your ear want it to go up to the 3, or down to the 1?
Does the 4 want to go up to the 5 or down to the 3?
Where does the 6 want to go?
The 7 is often counted as a chord tone but it may want to move as well.

Don't forget to make the rhythm interesting and let your ears make the final decision.
#3
Walk away from the guitar, think of something in your head, or better still, sing or hum something out loud.

I'm sure you've noticed that some of the guitar melodies in Knights of Cydonia are the same as the vocal melodies.
My name is Andy
Quote by MudMartin
Only looking at music as math and theory, is like only looking at the love of your life as flesh and bone.

Swinging to the rhythm of the New World Order,
Counting bodies like sheep to the rhythm of the war drums
#5
Quote by Patrick Curley
Don't forget to make the rhythm interesting


Great advice. I've just started drumming and learning the some of the drum rudiments has already helped me make more interesting rhythms with guitar.
My name is Andy
Quote by MudMartin
Only looking at music as math and theory, is like only looking at the love of your life as flesh and bone.

Swinging to the rhythm of the New World Order,
Counting bodies like sheep to the rhythm of the war drums