1) Do not assume anyone will know the rules.
I think this was my biggest mistake I assumed that since several members of Boston Trained band had played Black Powder that at least one or two would be at my table. As it was Kermit had some familiarity with the game and helped a lot but there were no experienced players guide the others it was all on me.
2) Less is more. My play tests did not show the game as being too big but on the game day it was. I think point #1 has something to do with this but noise and harder time constraints contributed as well. If I were doing this again I would make 2 stands = 1 unit rather than 1 stand = 1 unit. The total number of figures would have been the same (keeping the spectacle of mass that I love for this period) but units would have been halved reducing the dice rolls need to get the same thing done.
3) Special abilities are great but new players will not know to use them so don't bother with more than one or two per unit. A lot of the abilities can be simulated by just raising or lowering the commander's rating by 1 up or down, and that is easier for every one to understand. Alternatively other unit stats can be played with to weaken militia or strengthen superior units. This lessens flavor but makes the game more intuitive.
Of the special rules I used Platoon firing I would keep, Tough Fighters I would keep and Elite I would keep but all the others I would drop.
4) Make a turn chart and have it posted so people remember what to do and when. Mark roll for elite recovery(and similar attributes) on that chart or the skill is useless.
I would be interested in other peoples obervations and thoughts on running games at conventions.