I chose to paint and then, with the help of the sponge, silver paint to simulate the cracking. I do not think went wrong and with the advantage of being able to clean without damaging the painting because I used enamel paint.
I started painting the model. As I'm a bit afraid that by giving the oils the "silver" is affected, since it is enamel, painted the front of the model separately. It is always easier to remove the paint.