Very good advice from Asai as usual. The deep sea zones are very important to note when planning your campaign.

The North Sea is in contrast to vanilla, a deep sea zone that restricts which type of ships can enter and leave the Baltic. The Adriatic ocean is blocked off, further dividing the Mediterranean. And finally, the Gulf of Cadiz is removed so that you have to cross the Atlantic Ocean to get beyond the Gibraltar (Or conquer the Costa Verde zone to bypass it). You need deep sea capable ships to get by all these zones, which is the Caravel in the high period if I remember correctly.

I can only concur about the money shortage in MedMod. This is, together with much better unit balance and Homelands, what I like most about it. You can't just keep pumping units every turn non-stop and expand relentlessly to support them, but you have to carefully consider what you will need as well as taking risks when fighting other armies.

If you continue to wait for a moment when your enemies are weaker than you so that you can comfortably outnumber them (like in other mods), you get outproduced and surrounded fast, and could quite possibly suffer serious setbacks due to the much improved AI army composition.

When building armies and invading, take very careful notes on the enemies exact stack composition, his total number of units, the terrain and landscape of invasion routes and other variables. In MedMod (and I guess in SW), you need to maximize the advantages that allows you to take on superior and larger forces such as the killer Italian spears or the fearsome French cavalry.

War is costly and carries serious consequences, like it should

Also, considering what provinces to invade is more important. Study the potential of provinces you wish to conquer, and set top priority on certain ones. Trade centers are a good idea to set your sights on.

For an increased challenge (), you can also play with increased province rebelliousness. By raising it, the campaign becomes very, very strategic when coupled with limited income, forcing you to enter nerve wrecking battles that are absolutely crucial to win!