This is probably pretty obvious, but playing hard take out your immediate competition fast in the very early stages, until you've at least 3 or 4 provinces, if you leave it too long the stacks that the AI produces create serious expansion issues, while crippling your economy.

Also early on play with the general(s) roles, switch around the generals, (can't remember the name...), titles(?) so that you are maximising their potential based on where your clan is at, fighting, building etc. (actually played about 8 games before I even found this option).

Couldn't agree more with everything posted previously, would add the proviso to be very careful who you ally up with, I try to keep it to one or at most two other clans, having your honour wrecked makes dealing with others harder.

Churn out some bow ships as soon as you can & snap up trade routes, (sea warfare is a costly hassle), generally if you're on a trade node the AI seems to leave you in peace.

This may not be to everyone's taste but I used to do it in STW so why not part 2, if you are going to attack somewhere, why not send in the monks & ninja's first, stir up a revolt & take the province from them, that way you can take land without even having to declare war.