First off, there's a load of great guides here already with lots of info and advice to tell you all you need to know. This isn't trying to be one of them
What this is about is what attitude you should have for the game, and that's something that ultimately comes down your personality and how you want to play the game anyway, so don't take this guide as anything more than a suggestion or a view to consider. But it might help you, especially if you find yourself as a new player on a mostly full server crowded out by war monsters who can squash you like an insect. It is possible to beat those guys, and you need to make full use of all the technical info that's here, but you also need the right attitude. OK, here goes.
How you need to think of the game is, consider it a massive zero sum game.
What's a zero sum game ? A zero sum game is one where, for every winner there is a loser. If you're winning, it means someone else is losing. And if you're losing, it means someone else is winning. There's no middle ground - and every decision you make is either helping you win or helping you lose. The winners equal and cancel out the losers - hence zero sum.
For example, if you do something as harmless as taking an oases, you've stopped someone else from taking it. So that helps you win and will result in someone else somewhere losing. Even if no one needs that oasis - why ? because you'll build with the resources, get prestige, climb up the ranks, take up someone else's spot and make them move down (relatively). So they lose, you win. Farming forts is more obvious. If you take the resources, it means no one else will be able to take them. And if someone does that to you - takes your oases, farms forts which you need, then he's not just helping himself win, he's helping you lose.
The classic strategy in a zero sum game is this: you have to do two things, and they might seem upside down but it does make sense:
1) Stop other people from winning
2) Stop yourself from losing
If you understand what that means, you can see that you can win even by AVOIDING combat altogether. If you want to bring someone down, take resources from forts he farms and take oases. Lock him down with a single cat if you think its a good move. If you're blocking his ability to win, then he's losing. Farm and take resources from inactives and forts, even if you don't need them - because you're stopping other people from getting them. Put them on the market if you don't need them.
And to stop yourself from losing - that goes hand in hand. Avoid combat unless you know you're going to win for sure. If someone attacks you with a monster army, send your troops hunting, make sure your cranny is maxed, the resource level is low. Then you're spending your time hunting and getting money, and he's wasting his time attacking you so you win, he loses, and in the long run you'll climb up ahead of him.
The game doesn't play out from battle to battle, it's how you plan as a whole that really counts.
Anyway, as usual, if anyone out there want to add/ improve/ criticise, you're welcome