1) Max research for your University Level, particularly Combat and Defense Sections
2) Attack based gear... Arbitor, Glacian
3) Don't add unnecessary power. (siege units, opening quests, rss buildings, overleveling your hero)
4) Level your wall, and each building inside your wall... Preferably Barracks but wards and banks can work with good attack gear.
5) Don't rebuild traps after you capture and opponents hero
6) Only build the highest tier combat troops you can
7) Luna, Oracle temple city assault, adventurer research, mercs can give you an incredible advantage if you choose to go that route