Here are a few tips i found while playing :
- Use Diplomacy to make them declare wars on you
You may ask "Why? I just need to declare war on them!". Yes. But here's the situation for example :
You are France and at war with England and Russia. You want invade Hessen to annex it. Hessen independence is guaranteed by Austria. You don't want a war with Austria.
Just "insult" Hessen until your diplomacy with them is negative and wait. There's a very good chance they will declare war on you and you can crush/annex them without problems with Austria
- Manpower is a major issue, gold isn't. Build guards as they are the best use of manpower. You still need a bunch of artys and some cavalry but guards shall be the bulk of your armies (disband inf/light inf)
- Annex is much more efficient than satelitte in all aspects but one : it cost less in a peace negotiation to satelitte than dismember a country.
So, it's faster to satelitte a country as you don't have to take a piece of them, wait the end of the truce, war them again and annex. But they don't join your glorious empire and keep their manpower for themselves. You shall not accept that
- When you beat a decent army, don't let them recover. Pursue them and destroy them to the last man. Else, the army will replenish and you will have to fight it again.
- Speed if crucial. As such, i usually create my armies with their speed as criteria.
* A type of army with speed of 0.9 (arty/supply) : siege forts/city my main armies left behind
* A type of army with speed of 1 (guards/horse arty/supply/cavalry with speed 1.25) : my main armies which search, fight and destroy ennemy main armies, siege the forts/cities once it's done. Horse arty is less powerfull than regular one but will do the job
* A type of army with the 1.50 cavalry : get along main armies, lend a hand to defeat ennemy main armies and hunt single regiments who try to sneak behind
* A type of army of 1.75 cavalry : scout around to spot ennemy main armies and clean single regiments on the way
- Adjust the size of your armies to the needs
You never need a permanent 100k+ army. You better have several armies running around sieging forts and gather them when you need
When defending, you can have larger armies
- Being at war isn't a problem for your war attrition. Only loss will add to it.
So, you can be at war during all the game with no consequences and, in fact, you shall allways be at war with someone to conquer more lands
- As Russia, you can join Austria against Ottomans. I tried it several times and you have an easier war against Ottomans but Austria tends to get grounds in Greece.
I tried to let Austria and Ottomans bleed each others for few years; most of the time, they just stall the other. In the meantime, it's easy to crush Sweden (with few ships to help) and Prussia. Then, Russia can crush Ottomans without a problem and boot Austria if need be
The only but big downside is that with Prussia and Austria out of the picture, France doesn't have any decent opposition to slow them...
Finaly, i think the best way is to bring immediately all Russia army to Ottomans borders (leave east wide open), build as much arty as you can to lower siege time and blitzkrieg them up to Greece. Then, wipe the rest of Ottomans and annex every land between Austria and Ottomans.
That way, Austria and Ottomans won't be at war, Austria can fight France and you can feed on Ottomans for years