The longer you play, the more you will develop your own sound even without you realising that but other people will recognise you from your playing, all the other musicians in your band will to so the very Unic sound will come all by itself, don't worry about that.

As for the style you need to figure that out with your band members together.

Key for succes is however that you need someone at least that can write good lyrics and someone good at finding melodies for those lyrics and someone good at creating an arrangement and explaining that to the rest of the band and all off that is the difficult part.