Playing as Poland-Lithuania (Tips/Strategies?)

[Doomdark]

If you want to get more colonists then you have to gain more provinces with ports.

No. That has no effect whatsoever on the rate of colonists.

Upgrade your existing ports with shipyards.

A shipyard in EU is a naval manufactory. That won't get you any more colonists either. What you need is a wharf. Possession of one or more wharves will give you exactly one bonus colonist.

Conquer Ragusa.

Now this is true, because there is a wharf in Ragusa in the regular GC.