How to be a commander your team needs

I am a level 7 commander and I relatively new to the game relative to my peers. To my more experienced counterparts, what are some things that makes a commander successful? How should a commander control the field on a team that is strong and aggressive at destroying friendly garrisons. Also how do you help your team uproot a heavily dug in enemy force? Should artillery guns be used more, rarely have I requested a squad unit to run one.

More on the aggressive and strong enemy force destroying friendly garrisons, how do I even keep up with this and dominate?