Notes for permanent Spain player:
1. Don't build cannon this early. Yes, they're nice for sieges and assaults but they're an expensive luxury.
2. Don't prioritize production colonies over basetax colonies this early. Yes, they will be rich later on, but if you'd focused on basetax over production you'd have a census of 800-1000 now. There is NO excuse for leaving base 8 provinces uncolonized for 100 years.
3. Make sure you build governors. The establishments tab in the ledger helps you find provinces that haven't had them built yet. It's a waste of deflation not being anal about this.
4. Don't put troops in places where they won't do any fighting. Malta and Sicily is case in point. If your enemies want to take these islands, they'll do so with or without the small garrissons. The troops are better put to use where there will be actual fighting.