To 'make a good band' in the sense of having the possibility of getting anywhere with the music, you need to start writing and performing pretty much all your own material right NOW. As far as I can tell, with most succesful bands the musical style for each song is mostly led by the person (or people) who generated the song in the first place. This is because the songwriter generally has the most coherent idea of how the song will work in a full band arrangement. The songwriter certainly doesn't have to be the singer.
What I'd say is write a load of original songs, identify which are the best songs and then let the style and quality of those songs determine the band direction.
It's no use trying to be a death metal band if your songs all sound like ABBA and it's not much use going on national tours if your songs turn out to be completely **** because nobody is going to follow you.
That's the scientific approach to being in a band
