1) Write synesthetic characters. Most descriptions of sensory crossovers are by non-syns, and it shows. Rather like erotica written by an asexual; or military fiction by someone who read a Tom Clancy book once.
Never mind the writers who think synesthesia is about replacement of one sense by another, rather than one or more other senses added.
I have the personal experience.
Finding out how to convey it is another matter. It might require a good deal of work.
2) Never mind trying to get the future right. Write about futures which I think might happen.