There are 2 paths to take with Toku.
1. Luck out with a close metal source and a close AI. Axe rush keeping only the best citys. Make sure not to over expand. Tech to Samurai. Dominate.
2. If you have space just Tech peacefully to Samurai, then Dominate.
Toku Teching? You should go CE. He can get early Pottery. I strongly recommend cottaging the capital. You can then switch to Bureaucracy for a big boost which times nicely with Samurai expansion. Don't meander with you're teching. Just go for the samurai. (After worker/econ techs of course)
Toku Expansion? Toku's golden rule is Dont Crash the Economy. This is because he has nothing to help him get out of a crash except possibly a pillage/razing war. Only build the best city's. Make sure they are profitable. With Toku you need to be stingy. Until Samurai you need to be a calculating penny pusher. You will expand slowly and probably have less citys then the AI. This is fine, japan doesn't need a big empire to conquer.
On Samurai. They should destroy everything in their era. A good trick is to build Swordsmen and then upgrade them the turn you get Samurai and rush. If you can get 1 GreatMerch and trade mission him that would give you enough gold for 10+ upgrades. You should catch the AI before they have maces, and maybe even X-bows.
Post gunpowder Drafting is you're friend.