when i first started playing risk i played lord of the rings risk the boardgame and they used a couple of very good rules that are very simple to understand and use.
1) they had a stronghold rule. key building locations in the films, like helms deep and weathertop, had an additional +1 to a die roll defense to represent their defensive benefit
2) they had captains. a captain was a different shaped figure that added a +1 to a die roll on attack and defense
while the captain rule will be difficult to represent on the board i think the strongholds rule will be very good on conquer club and can even be used on other maps as a option when starting a game