LOL play on extreme.  Maybe I should be playing on Novice.  How many turns did this happen to you?  Were you able to grow yor city into level 2?  Did you start your starting city near a fertile land?

Set the map bigger, that'll give you more room to work. Also if you find resources hard to find start doing adventure tech research, one of the options makes extra resources appear and it helps a lot.

Finally - just to be sure, you are building the farm upgrade on the fertile land tiles (and other upgrades on their tiles) right? You'd be surprised how often people don't realize that you have to do that. (Click the fertile land once it's in your city bouandry and click "build").

If your armies are in trouble, make sure you're doing warfare research for new equipment and squads. Then when you go to train units, you can design ones that use new weapons and are stronger.

I disagree with this. They can save you some worry. If you're about even with one enemy and want to wipe them out, by all means NAP with the person you don't want to fight at the time. That way you're good for 20-60 turns or so or whatever it is to focus on your enemy.

NAPs in this game are not like NAPs in Civ. You can't break them whenever you want. What they are, though, is a free pass to ignore that enemy and focus on other things instead, and when used strategically (especially once the AI gets less dumb) it can be highly advantageous.

I'd say...

1. If you use Adenture tree, use it only for the techs that reveal new resources and never the Heroes or Quests. That will reduce the "noise" of lots of hard monsters making it more difficult as the exploration branch doesn't create new monster spawns.
2. Having your Sovereign running like crazy to explore while you have a Pioneer being built is good too. Fertile patches are best, gold mines second. I'd put iron mines third and everything else as you see it.
3. Go for Party tech in Warfare. That and some savings (and the default equipment options) are the foundation for some nice armies. You may have to stop developing your cities sometimes. Experienced troops aren't so important when what you really want if offensive power. Weapons and armours are good. Cavalry only if you see the resource.
4. City bonuses? If you have Lost Libraries and similars, tech bonuses are fine but most of the time, gold option seems best to me. As surprising as it may sounds, I haven't tried the Guardian option yet so not sure about it.
5. Get some Champions. Farmers are top prority (unless you have tons of Fertile lands) but you shouldn't risk them in battle. Any other champion should be go with your Sovereign and be turned into Channeler as soon as possible, so they have more level ups to get extra Essence, Intelligence or HPs. Having some Channelers will reduce the need for Archers and with some magic research you will get magical area artillery, so it's important to be able to hunt down bandits and similar easy preys to level them up.
6. If you get any summoning spell, they are of the best things to can get. Even the humble Summon Familiar can give you a nice meat shield (and fast way to increase the rating of your army).
7. If you invest something in diplomacy, getting Diplomatic Capital will give you the option to get another balancing factor against the other factions. If you have more than them, they will respect you for it.
8. Non Agression Pacts are you friends if you can get some.
9. If the game lasts enough, Dynasties also improve relations. And if those dynasties involve grandchildren, more bonuses.
10. Avoid Kraxis at all costs. Those guys, at least in my games, get powerful very fast.

imho and considering the current AI in Normal.

Maybe I understood it  wrong, since english is not my first language but do I not loose own essence when I turn champions into channelers? So is it maybe not a bad idea to do it?

Ah see, but how can I get it easy back? I think this far the only way to get some is to level your channelor up or? Or is it not permanent removed?

Ah thank you, guess the essence bonus explains why one of my childrens had just an insane amount of Mana compared to myself. I guess in that case it is a good idea to start with high Essense or Wisdom when a Channeler is created. MAybe I was just all the time to much worried about loosing my Mana for no reason, since not noticed that you can actually level it up by the units you gave it to.