TheOcularInvisible wrote:I put my vocal samples into the browser, right click and open in slicex. Then it's pre-sliced and you don't have to worry about it.
I prefer this over going through manually with Edison or Audacity, but don't be afraid to move the markers around. Slicex isn't perfect, never trust an algorithm to make your music for you.
Look for longer, drawn-out notes and make your samples as long as possible. Put the start marker as close to the beginning of the syllable as possible, and the end marker as close to the next syllable as possible. Seems obvious, but you want to get the most out of each one without cutting it off (unless that's what you're going for - whoa, I just had an idea for a neat stuttering effect!). If there's heavy vibrato you may want to consider some slight tuning in Melodyne or Newtone or whatever. Just keep in mind that there are more ways to use vocals than just taking out vowels and putting them on the piano roll. Go against everything I just told you if it sounds good. Be creative!
Also, kind of important: if you do use Slicex,
uncheck auto-dump. Slicex deleting your melody because you slightly adjusted a marker kinda sucks a lot.
EDIT: Little more on the creative process. It's really similar to writing a melody, you're just using a sampled voice as your instrument. With that in mind, I find it's easier if you remember where certain notes are, especially the tonic. At that point it's exactly the same as writing any other melody, except your notes are generally shorter and the piano roll is a bit jumbled.

Familiarize yourself with the samples you've got and have a general idea of how it's going to sound. Tweak the pitches if it works. Make vocal chords by stretching and pitching longer notes - who needs expensive choral libraries? Basically what I'm saying is, go nuts. Don't limit yourself more than you already are.