>>133972good start is to check the songs in the thread that we posted, otherwise you might wanna check the oldies, songs by lamaze-p, owata-p, supercell etc. most of these can be found in the OST of project DIVA. older songs also tend to be based on the character singing them, modern ones dont care about that. here's how generally each character goes:
miku - she's a highschool idol, song tend to be the catchy pop type
rin & len - often in a duet, their songs are often about them doing chaotic things, however oldfags love incest so a lot of incest songs as well, and for some reason, dark songs as well
meiko & kaito - they often sing ballads, they are like the old generation, mature themes
ruka - shes a diva, like madonna or some shit, she's the least popular and i don't see her often
neru & haku - fan characters that were endorsed by crypton and are now known as fanloids, neru is a tsundere, haku has a severe lack of self-esteem .
other characters are not 'loids per se, but UTAUloids and synths, however everyone calls them 'loids anyway (there are also other vocaloids but they were not made by crypton, like gakupo)