expansion
1: finish of ito
2: keep sagara of your back (hostage, trade agreement etc)
3: finish of otome and then shoni
4: unify kyushu.
5: Consider carefuly where to expand, shikoku is CRAP in terms of economy gain but is a good naval defense (no chosokabe sea invasions). Best option, atleast on hard and lower difficulty would be to recruit 2 stacks (another 2 defending kyushu) to take iwate, ugo, miyagi etc down to and inc. fukushima as these are easy to defend and provide a good income boost. It'll also force your opponents to split their attacks during RD or allow you to attack them from the rear. (either way will distract them).
Other option is to hold the provinces around kyoto as many got fertile and above farms, ninja bonus etc.
economy
1: get those trade nodes. Upgrade to T2 dock at turn 1, then T3 dock as soon as T2 dock is done. Recruit a fire boat asap and recruit 1 every turn til you can recruit trade ships. send the fire ships to capture trade nodes.
2: Sell military access to sagara, its an additional 500-1000 koku every 5th turn. (so yea, sell 5 turn access, try first for 1000, then lower/increase depending on if its moderate or high success chance)
3: upgrade that farm, upgrading farms to stage 2 (average and above to stage 3, fertile to max) allows you to upgrade castles which allows both market and sake den/temple/church (temple/church decreases time needed to research chi arts = quicker economy based arts learned = more koku earned especially at later stages).
4: trade agreements, get as many as you can, dont spend the income on army upkeep. develope your land. remember to send ships off the trade nodes to get them to accept. Then send them back onto the trade nodes after you're done with trade agreements.
5: balance your army. Ashigaru works very well early on, but later needs backup from stronger units. Katana samurai is your friend due to the reduce cost. Remember to bring backup against cavalry. However you cant field samurai only armies at higher difficulties, ashigaru backed up by key samurai works well.
Lands:
1: Get kyushu....all of it.
2: Develope satsuma and bizen? bitchu? the northeast most of the kyushu provinces to unit producing provinces (high tier castle, encampment, all that shizzle.)
3: Consider if you want to use cavalry, if so use hyuga for cavalry production, if not stick with no-dachi/monks and use hyuga as income province.
4: upgrade to warehouses in the 2 provinces here to boost income by trade.
5: markets in all, temple/church to boost chi learning rate, sake dens later if you want ninja's or the 200 extra income once chi arts are learned.
6: Kyushu is strong, strongest region of japan. However the surrounding lands are rather
. Shikoku us poor, no cool bonus appart from cheaper ships. bad soil. on main jap. island there's aki nearby, and another province north/northeast of it with a gold mine but most of the provinces on this peninsula near kyushu got very bad soil. On the other hand, if you dare splitting your territory you can gain 6 excellent territories on east side of japan (iwate down to fukushima + sado), these boost your income greatly and if you want to produce high quality or cheap armies, armies with high morale you can do so here (shrine, smith and iron mine). sado is easy to defend, got a gold mine. Other rich area is around kyoto with owari, omi etc having good soil, ninja bonus but is even worse off splitting wise.