Publisher and game designer Chris Pramas has written a useful article on Running miniatures games at conventions.
The article gives some useful insights.
When I was about 12 years old, I “designed” my first wargame scenario. I tried to recreate the Battle of Kursk using Avalon Hill’s classic Squad Leader boardgame (I know, I know; I was 12). In practice this meant setting up four boards and filling them with as many German and Russian tanks as I could. My brother and I tried to play it and of course it was too big and unwieldy to finish. My attempt was a failure but it taught me an important lesson. Designing a good scenario takes more thought that just using everything you have and yet this is a trap many big games fall into.
Chris Pramas runs publisher Green Ronin, which published the Dragon Age tabletop RPG this year. You can hear more from Pramas in the Out of Character podcast episode 66.