For suggestions of general game progression, refer to the thread i made in the Spear section as a lot of it is largely general. The only thing to ignore is the bit where i say throw out the arty, coz you are the arty.
Otherwise the same formation applies;
I will always maintain that sething two cannons is the most awesome looking thing ever. If i were a cannon main i'd try sething a cannoneer, arty and cannon main for more epic boomy action. The only problem with doing that is as you get higher in levels the single target damage value per cannon shot is low as hell as for some silly reason, cannons are low in general atk power. However sething 3 cannons is THE ultimate 3v1 mob cleaner.
It LOOKS damn good, even though it'll never be the best in damage, i'll maintain it's the best in LOOKS.