Lisbon nights

We grab a few days away over the school break, and travel to the coast of Portugal and then south to Lisbon. I've been given a set of four warm grey double-pointed Promarker pens, and am still not sure how to use them to best effect.
This view of the square at Rossio from across the road from our hotel one evening (while the others slept, read and revised) is a case of trying to find out how I can use them with the black pens that go everywhere with me. That feeling of now knowing quite what you're doing can be an enjoyable one. Which pen do I reach for when I put another down? What makes things go forward and back? When to use the chisel point or the bullet point? How much tonal range is needed? Which restaurant are we eating at tonight?