Every good games have tutorial and I do think Elemental is a good game so I wanted for those people who are loosing against the computers to make a little something to make their experience of the game more enjoyable.
Help is welcome as this tutorial will be my vision of this game and how to play it in order to have a lot of fun in it. Let's start with the kingdom as I don't really know anything about empire.
Part 0 : Creation of your sovereign
The removal of the organized talent has made this part of the game more interesting. Actually the best way to play before was to optimize the sovereign's move and to select the organized talent but now you can do everything you want, it will be viable. The best tip I can give you is : Roleplay.
There is this character in a fantasy book that you like, just create it and then play with him as if you were him or maybe create it yourself. I think it's a funnier way to play the game than just optimizing a munchkin but of course I can't say what is funnier for you.
Part 1 : Create your borders
I can't understand all that people talking about city spamming. Do you think a powerfull country, even in fantasy books is just made of one or two cities ?
Cities have the great advantage of increasing your influence in the world map. You have to take as much territory as you can, it will give you more gold mine, horse, metal mine, materials, tech, arcane, shards, etc... Don't hesitate to spam pioneer. You want influence, influence, influence and don't want to see opponent cities everywhere on the map.
Of course during that time create buildings, visit everything with your sovereign (not naked, you don't want him to be killed by a wolf, the best is to look after the fire dart before having its familiar, buy one weapon and to have someone with him, maybe you can even use one city level to create a random unit sometimes they are very good and will make fine scout)
Part 2 : Increase your revenue
A good way to increase revenue is to look after the adventure tree which reveals more mine, more foods. Now you understand better why the create borders is important, the more territory you have, the more these technology will profit you.
Part 3 : Look after invocation book
You want the invocation book, you don't have a lot of money to spend in wages or to train unit, so you are looking after invocation which will be your main force for a long time. You can train scoot at the same time to discover the world and see where to go next.
You also want to marry yourself as children are far better to sovereign, they are expendable commandant, their death in ennemy borders won't entail the end of the game and they often have mana and health regenaration during combat (what else ?)
Part 4 : Defend city at the borders
Now you have to design unit with very high defense, you will enjoy all the "miss" during combat against loads of computers troops. During these combat, the priority is to destroy the most numerous troops, as it will decrease its A/D. Create squads of these units in borders cities, especially near country you want to invade (you certainly want to invade the wealthiest country, it's showed in the foreign relation tab)
Part 5 : Have fun
Now you have a good economy, a good defensive force, a main force with some invocations which have gained some levels, there are several ways to go.
- a magic way, imbue a lot of champions with you sovereign and research offensive spells
- a warlord way, with big army with the best weapons and armors.
- a diplomatic way : the dragons!!!! There are very expensive but can be squaded (graphically it looks like a four head dragons) with a spell which do all the Attack value, it's very efficient.
You can mix these strategies also 
I think that the warlord way has to be used if you see horses (but horses don't exist). Imagine loads of paladin conquering the ennemy village for the dominion of their well loved sovereign mouah ah ah. More seriously with horses you have better mobility that with invocations and I don't like to see ennemy sovereigns succesfully fleeing my army!!
Don't hesitate to add your strategies and comments 