It's not by creating massive armies, it's not by creating insanely huge fleets.
It's by diplomacy and skirmishes.
Garrison a minimum of 7 companies of soldiers in every farm you have and capital building.
Step 2. Gain diplomacy with the Ottoman Empire. To the point you create a military alliance
Create raiding parties, and attack completely random farms, factories, docks, everything but the capital building in each territory. Reason why, is because this, over-time, bankrupts your enemy.
Attack the Ottoman Empires primary enemy, Russia. Send a small fleet with a medium sized (10-15 company) army, once the army has landed, split them up into 5 different groups. Those are raiding parties. spread them across Russia. It will divert Russian Forces away from Ottoman Empire, which, everytime I've done this, causes the OE to destroy Georgia and the other country by it, and begins full expansion into Russia.
Once you have completed step 4, begin making peace talks with the Barbary States. They will start producing even larger quantities of ships, and start pounding down everyone elses ships but yours.
Become allies with the Mughul empire. Send about 40 companies of Soldiers, get military access with the Mughul EMpire, and begin attacking and destroying Martha confederacy. do not take cities, just destroy their country sides, send their armies in disorray. Mughul empire will finish off and secure all of india, from this point, they will start constructing ground troops and start attacking Persia, in most games so far doing this, persia is wiped out. Leaving a super power Mughal Empire, and Ottoman Empire. All of Russia destroyed, and both powers start making their way westward.
Step 6. Bring all attention left tot he colonies, since Europe will now be steamrolled, except for your faction, all the others will slowly, and gradually be erradicated. If you weren't already, start the Island hopping campaign. take all of the islands first. If you already have territories on the mainland, good for you. Expand into other mainland territories. Remember, the "Colonial Nations" are weaker than the super power nations in Europe. And with the Ottoman Empire taking the brunt of combat, and Mughal Empire right behind it, well, yeah..... They will both go super navy with Barbary States. So all you need to do, is reap the benefits.
Step 7. secure the territories needed for victory conditions.
Step 8. You complete the campaign.
Step 9 if you want even more fun, give the Ottoman Empire fully developed territories in the Americas. They will start sending entire armies with stacks of 20 each from the ME to the Americas and wipe out everything. Not joking, the Ottoman Empire takes off the most dramatically after it's been given territories in the Americas.
Give them territories in Western Europe, and it makes it even faster for them to take over Russia. They will destroy everything between them, and the Ottomans in Eastern Russia/the Caucases so they aren't scattered. I've found this may be an actual mechanic to unit borders between territories.
Mughul Empire is the same way as well. If you have territories in Western Europe to give to the Mughul EMpire, they will explode, too.