Strategies just come with ways of thinking. Therefore, some strategies might work for some people and not for others, therefore there might not be much we can help you with but I'll give it a shot.
Simply training all your creatures to highest level possible does sound very plain and simple. Perhaps you should go a bit more on the offensive aggressive side and do frequent attacks, try taking some land or something. That should at least make things more interesting with battles. Look at your spells and use them. With conceal you could sneak some Imps over to claim his land.
You could also use the Scavenger Room and have a scavanging war back and fourth. Scavanging demands a bit more money so when you seek more gold, you're probably going to run into each other by surprise and that is always interesting as it knocks the difficulty up a notch.
Just some ideas, explore the game some more though. By the looks of it, you really seem like a bit of an inexperianced player if you're just training all day long then fighting with brute force. No offense or anything really.
Have you played Deeper Dungeons by the way?