It depends: what is your country (income, ressource, etc..), and what are your long term plans? Then you have the answer. However, few general guidelines that seem to be common to every country (??).
If you are austria, you most probably should emphasize on infrastructure and land tech: develop tax collector, and then build weapon factory as much as you can. As your main ressource is iron and copper it will increase your income. The gain in land tech will be very useful in the most probable wars against everybody around.
If you are france, try to be more equilibrated and emphasize more on commerce (distillery first) as you most probably try to become a colonial empire.
Basically, have a look to your provinces to get the more efficient economical development.
If you are england: economy and colonial development!
etc..
As a general, develop tax collector and factories. I'd say that factory in an appropriate province is more intersting in the begining than judge: you gain 12d plus the techn advantage and -1% for rebellion for a cost around 800d. A judge is 100d, 1d extra and -1% rebellion: if you built 12 judge you'll spend 1200d, gt the same income increase, no advantage on tech devl. On the other hand you'll get 12 provinces with a -1% rebellion... Seems to be quite useful in some cases (low stability 'cause of wars, civil wars, events? might be more intersting for some coutries...).
If you are a small country with low income forget about factory, and try first to annex wealthy provinces around you if such exists (with CoT or gold mine..). Never start to conquer poor provinces as a small country unless it gives you access to wealthy next-to-conquer province.
You should (aim to) set inflation rate around 0.10%/y, and build an army such that your income/month is around +0.0 and try to save 10 to 20% of the annual budget in cash year per year. That means that you spent 90 to 80% of your annual income in merchant, diplomat, army and navy. When you saved enough money build a factory, put somewhere a tax collector, colonist, judge etc..
Concerning trading center and govenor it is not that expensive so feel free to use them at will (governor is as expensive as tax collector but you get them later in the game, and at this time money shouldn't be anymore a problem (hope for you

).
After a while, you'll most probably realize that all that is very too basic and is not good for your own country.
