Rock vocals can appear to be an easy task, but they're most likely the hardest vocals to capture. Many rock songs have different levels of vocal intensity and this makes them tough to record. Unless the vocalist is a seasoned studio professional, you're going to wind up doing a few different takes and then composing a final track from multiple playlists. So, let's be up on how to approach this task.
First, have the singer go all the way through the song and get a feel for the level of intensity at each part of the song. Mark where there are significant changes to the vocal intensity. Start with the softer / quieter parts of the vocals. Position your mic so that there is no capsule distortion. (See my earlier post on mic placement) save the screaming / high intensity parts for the end. This will save the vocalist's voice and not put too much strain on the vocal cords.
Now a big part of the recording is emotion, so you need to encourage the vocalist to express their emotion. Listen to the recording and decide if you believe the lyrics and feel the emotion that the music is conveying. Rock vocals are the glue to the song and they need to be convincing.