Ajahn Sucitto takes a deep look at the practice of wise concentration (samadhi) and presents an approach to it that is much different than we might anticipate. Rather than a grim focus on forcing our minds to concentrate on the breath, he presents it as an embodied practice of joy and awareness. You can find his article here: Samadhi is Pure Enjoyment
One Mind Dharma has a discussion of concentration meditations on their website. It includes a list of types of meditation that are suitable for deepening our concentration as well as some guided meditations. They also include some suggestions for the practice, several of which echo those from Ajahn Sucitto. You can find their article at this page: Concentrative Meditation