Basically everything in the title, i'm the songwriter in my band and i come up with interesting verses i just can't nail choruses. they just always fall flat compared to the rest of the song, could any one give me some tips or ways to improve my songwriting

I would suggest listening to really famous pop songs, it may not be the music you want to make but the energy behind those songs alot of the time comes purely from the hooks so they are good reference points and to give you an idea of what a successful hook sounds like.
hooks are all about catchy. Catchy chord progression, catchy riff, catchy vocal part. Catchy is all about what comes naturally - play some chords, hum whatever seems to come naturally 'in your head'... that's kinda how I do it...
Try non-lyrical refrains such as "shalalalala", "lalala", "bababada bababada!"