Rob's guide to effective retrospectives
Be well prepared
Facilitation is a skill
Rotate the facilitator role
A big smell I regularly see and hear about is it being one person's job (usually a scrum master or project manager) to organise and facilitate the team's retrospectives. When this is the case you will often find a general lack of engagement or enthusiasm for retrospectives from the rest of the team. It may be one person's job to make sure they happen and everyone turns up, that does not and should not mean they also have to run every retrospective as well.
Instead try and get everyone to take turns facilitating. Not only does this ensure that no one feels they're always being driven by one person's agenda