We set up a Kanban-board. We start every week with a commitment, team members make an estimate how many points they will have done by the end of the week. Points are not measured as working hours because it would be different from person to person. We try to have a common measure of complexity points, it doesn't have a specific meaning, it's just an abstract unit. We just had enough planning session together so that two team members will probably give a similar estimate of a task in complexity points. This is further reinforced by the weekly feedback session when we sum up the actual points we delivered and talk about what had caused the differences between the estimated and the actual values.
The commitment phase is pretty frustrating and painful for me because it's usually me who says the lowest number. It makes me feel dumb and incompetent.