Here are some tips and guidelines that we all should try to follow to make everybody's life easier and save everybody's time and nerves 
Please understand that below are just some guidelines of how we can be more effective, how to get more out of the meetings and how to have short and constructive meetings. Would be great if we all acknowledge those tips.
Be prepared - prepare yourself for the meeting, know what the topic will be and read all the connected materials ahead of time (there should be a link to a page in Confluence or initial meeting minutes prepare with outlined agenda). This way the meeting will be more effective and no time is wasted for explaining and introducing all the background (to some extent this will still be done, but considerably less).
Pay attention - while in the meeting, pay attention and be active. Worst case is when 20 minutes into the meeting there comes a phrase "so what is this about?" or somebody brings up topic that was already covered 10 minutes ago just because he/she was not paying attention at that time. For the same reason it is very inconvenient for all the participants if you walk in the room 15 minutes later/after the meeting has started - please try to be in time.
Mobiles - worst are the mobiles, please turn them off or set them to silent mode. It is very distracting when mobiles ring and even worse when you pick it up and start talking to somebody. Whatever call it is, it can be handled after the meeting, everybody will understand if you can't pick up the phone at any moment and will simply call back in 10-15 minutes.
Avoid distracting others - for an example this would include chatting with the person sitting next to you, first it distracts everybody else, it takes your attention away as well as the ones attention you are chatting to. Short comments are fine of course, but try to keep any longer discussion for after the meeting.