I have just returned from ARCHES, a small European conference in audiology. The organizing comittee (which my team is part of) follows a set of self-imposed ruled which I think should be a model for other international scientific meetings: (1/7)

1 - minimal registration fees, we don't need fancy dinners or luxurious venues; (2/7)

2 - senior members do not present their own work but an overview of the work of their research team members; (3/7)

3 - friendly atmosphere and respectful scientific interactions so that junior attendees don't feel afraid to present their work or to ask question. (4/7)

4 - Of course the last one is an implicit rule arising from
the fact that ARCHES is a small "private" conference (only members of the organizing teams can attend). (5/7)

Yet, I realized that most of the questions were asked by senior researchers. I discussed this with two PhD students from my group who told me that they don't feel comfortable asking questions about topics they may not be familiar with. (6/7)