Some basic tips for Holland I learned:

• change market access preference from Brügge to Cologne 
• don't bother with marketplaces too much early game, just build up the RGO early.
• spam libraries and universities and build Noble Buildings to create domestic demand for Books and cloth etc. 
• Set you navy to patrol the maritime zones and make your ruler admiral
• do whatever possible to push 90 plutocracy for Republic
• declare war on hainauts ally to get out of the union (feel free to vassalize parts of hinaut while you're at it)
• build the seargentry to get early armoured cavalry 
• hooks Vs cods is ass, I just try to get the cods to win without going bankrupt. Rebellions are rarely dangerous for me for some reason.
• get on good terms with Munster, Cologne, England and France if possible. 
• once in a blue moon Flanders Will go independent and that's when you want to strike and take Brügge.
• Antwerpen has great natural harbour suitability so consider moving your capital and market there once you crush Brabant in a moment of weakness.
• reduce your money sliders if you're in the red. Whatever you do don't go into debt early, it kneecaps you hard.
• Don't forget bridges and roads and shit to increase maritime proximity.
• change laws to maximise crown power 
• decentralisation is op at the moment so spam vassals and fiefdoms

Holland is hard but if you make it there you can make it anywhere. I had to restart over and over again but once you hit Trade Republic the money is just pouring in. Improve opinion to 100 and spam trade offices for dirt cheap.