I am not sure if this belongs in the vocals tips thread since I am not asking to sing. But instead I have a problem. Everytime I write a riff or a lyric and try to match it. The guitar and vocals always have the same beat. Is there any tips for writing vocals that dont match the guitar parts, but still go with the song.
try listening to your favorite artists singing
some will go unison others diverge

'tis life
listening to your favorite artists is a great way to understand how others do what they do well. i have this problem too sometimes. what i will sometimes do to mix things up is record 2 vocal tracks. the first track will be sung naturally with the song as you are stating, starting and ending on the beat, then i will go back over it and sing a second line often in harmony with the first line but starting on the beat after or before the first one (or even earlier or later than that, whatever feels right for the song) then fading out the first "on beat" track. you can get some very interesting rhythmic alterations this way and it will feel very natural and not forced.