My present knowledge of this game is restricted to the battlefield. I am an MP general, and I will give you a rundown of where to go to learn some basic knowledge on how to win battles.

The AI is easy to defeat in battle once you get a feel for how to deploy men and how to move them properly.

I remember when I played my first online games in Shogun. The deployment of men, what men to take, and how to use them all made great sense after a few games. The funny thing was, I had beaten the campaign mode several times before I'm glad you are asking for tips, because I dont think the game itself can teach you that much in terms of battlefield strategy and organization.

Here is what I suggest you do to gain strong knowledge of battlefield tactics.

Step I: Read Skomatth's guide to Multiplayer battles. Tips can be gleaned from this and easily applied to SP. Some parts apply only to Multiplayer though. Here is the link:

Skomatth's guide
This ought to teach you some basics, covering the things you already know and maybe filling in on some things you didnt know.

Step II: Find some replays of online battles. Watch what the players do, and find the reasons for them doing it. STW: MI/WE replays can still be found online. Viking replays will be harder to come by. I know of no replays for VI that can be found yet, so you might just want to go online, play a few games, and watch the skilled ones compete. There is also a good chance that you could recieve a training session with a veteran. A few would be quite eager to help.

You should now have a feel for the way the game works, and the army compositions, deployments, and strategies that are favored by the game. Next, you will need drilling exercises that teach you how to use your mouse and keyboard to make your army carry out these tactics.

Step III:
Go to Tootee's site, Shogun Academy. That site has the proper instructions on the advanced movement and organization of troops. Grouping, facing, turning, and advancing large armies properly is all handled here. Learn the keystrokes and hotkeys you dont already know, and practice them in Custom Battle mode.
Shogun Academy

Now, you should be able to know what to do with the forces you have and how to do it properly after learning strategic basics, advanced tactics, and proper organization skills. It sounds like I just trained you for MP, but remember that strategies and deployments in MP are highly evolved, developed by the sum of the community since Shogun came online. It is unlikely there is any better knowledge than in MP.

If you have any more questions, just ask