Please post away if you'd like to write a small tutorial, give tips, advice, of how to create a mission - please post away :)
just a little teaser for you - you can read how a mission develops and what stuff is added... gvse is already quite busy with his Lumber Yard Mission (http://openworldgames.org/owg/forums/index.php?topic=733.msg9266#msg9266) and we're discussing how it works, what is needed, some links and examples... I find it very useful and a good way to see what it means to create a mission.
Nevertheless, I still hope we get a real How To going here. :)
Guys,
I have found this tutorial extremely helpful in revising my first mission:
http://www.ofpec.com/tutorials/index.php?action=show&id=14&page=4
It has been developed for Arma but all works more or less the same in A2 (sadly the example mission available as a download file will not w@&k in A2).
I have learnt a bit already so if you have any questions fire away and perhaps I will be able to assist. :)