I suppose TCX are building the foundations.
Start by adding the markets you want to serve (especially before anyone else gets there), then, when the routes start doing well, add in extra flights. Look at JFK. Started 3 weekly now daily, LAX and BOS went from 2 to 3 weekly (granted its only a small increase but walk before you run).
I'm hearing this isn't the only new USA route for 2018 though, with potentially 2 more to come.