I've just beentrying to come up with interesting art styles that I could use. I've been using a pencil tool to get that effect , and I think it does work.
The first one was me going for a minimalist approach to colouring whilst the colour doubled as shading. It mostly works for the large areas but anywhere that has too much detail looks clustered & like l couldn't be bothered to properly colour it in.
The second one I tried lowering the opacity of the pen to get a more pen & paper feel. I did this with the shading & highlighting, and it turned out well, but it was the one I spent the most time on.
The third one was block colours. This was meant to simplify the design & also reference propergander posters with their sharp snappy designs.
Over all I think if took the pen & paper feel of the second one and combined it with the block colours of the third it might just work. Also loose the heavy highlighting of the third one.