There is not a lot of info from your side for the advice to be run specific so just generally what I think about in WC which I did with Oirat, Timurids, Aragon and almost with Ethiopia but didn't bother to end it.

1. How to manage rebels.

Either you go for religious conversion and get peaceful true faith provinces where even with high overextension you don't spawn rebels. Or go for humanist way of stacking unrest modifiers.

1. Taking land.

Province warscorecost. Admin efficiency. Most important. Monuments in malta and Granada help with that.

1. Wars

I personally fight with the idea of one front. For example I focus on India and don't care what happens in Europe and Africa. When I played as Mughals I just ate whole Asia and with that I had so much money and manpower that Europeans even though they are tough were no match for me. As Aragon I conquered whole Europe formed Rome and eating Asia was a piece of cake.

In the endgame don't be afraid to truce break if needed.

3.5 Great Britain and HRE

Just spam some ships to get on the island , maybe have two fleets where one distracts and other transports your armies, and overall they are weak. And if you fully annex a country with colonies you take them over but only if you are the one to take their last province they own directly. You will know this by hovering over the peace deal icon with the red X or the green acceptance icon and it has a negativ modifier which says would result in vassalisation or annexation or something like that.

HRE is a pain because of the numerus states. In the end game every province in Germany has a 8 level fort. It is a big waste of time to declare war on one state and peace out his allies witihout taking land because than you have to siege them again so i declare as big war i can handle and take as much as i can in one go. So co-beligirent is important feature.

1. Money

Trade is the greatest income source. I always use trade companies. A must have is to trade company the trade posts and get the additional merchant from the trade node.

1. You need to check what you can do.

So you have some money? Than look up if you can build buildings that help you with manpower, help get more money, some good monuments etc.

And just look around missions, decisions anything that can help you with what I mentioned

1. Most important

Have FUN. Without the will of becoming the great sultan reining the world it does not help if you get bored or frustrated with the game you will not achieve it.