you don't need to necessarily use songs that haven't been used.
i think songs like

more than anymore
dare you to move and
halo

are used too much, so don't go for them.

something happy like 'in love with a girl' by gavin degraw
or 'crazy for this girl' by lifehouse

just flick through the songs you have, and listen to them carefully, see if you can picture it to a video, and then go with it.
that's what i do.

:)

thanx that really helps me ..i like the gavin degraw song you mentioned!!