I also suck with these : /

play your melody, envision the possibilities...and sing random crap that flows in your head :P

 

like 5 mins ago i just made a new verse to Hurts Like Heaven about getting wiped out my Hurricane Irene XD

Try to reproduce the melody of any song and play with the notes,or try to express your feelings singing or playing your favorite instrument,change the lines of a song... if you know scales and harmony and those shit is easy

Play with the music and have fun :P

randomly playing piano keys.

or find a chords progression you really like,

and fool around for a bit.

We have no time for fooling or messing about!

Find a chord progression you like and sing notes which go together with the chords and you've got yourself a melody. It works even better when you already have lyrics (assuming it's a song).

Singing is the best way and it comes instantly, if it doesn't, then it'll come within 5 minutes. But if you spend too long on it, then there's no point in keeping it going because it just won't work and won't go anywhere...many a song I have scrapped abiding to that rule.