Much depends on whether everyone in the team will be working full-time or it is rather a side arrangement for team members.
In the former case you have more options as most of popular agile methods can be applied in distributed teams. Scrum will help the team focus on achieving iteration's goals although you can find it hard to follow specific practices prescribed by Scrum, like daily stand-ups.
You can also go with Kanban and limit work per single team member, e.g. not more than a single task, or a couple of them, per a single team member.
In the latter case you need something which doesn't set many time constraints on the team as people would probably work irregularly, because of their daily jobs, private life arrangements etc. In this case I would go for Kanban which set focus on the flow which is quite effective approach in such situation. It is also very light-weight and adds minimal formalisms on the top of what you already have, which is another plus.