Right off the bat...



For absolutists:
 * model your country after North Korea (censorship, no freedom of speech, conscription, political prisoners, aggressive isolationist foreign policy...)
 * Take into consideration the far reaching effects of your desisions, even if you have, as king, utmost power.
 * re-open and subsidize factories
 * research military, cultural monuments
 * raise taxes to cover expenses (wars, etc.)
 * preserve religion
 * maintain serfdom
 * centralize authority (take nobles' power away, invest in government administration)
 * maintain military strength
 * If you feel obligated to.... attack weaker countries for control, show them who's boss
 * consolidate power-annex vassels and the like, and attempt to centralize power

For constitutional monarchies:
 * Depending on the restrictions of the constitution, raise taxes so that the people can still afford their daily needs. (Could do the same about ruling like an absolutist ^, exccept do not make large changes that would take away the purpose of a constitution)
 * Make your desisions based around constitutional limitations.

For republics:
 * Begin to see what your country consists of (people that are conservative, liberal, etc...)
 * Listen to what the people want.
 * Eliminate tariff barriers because it would encourage trade.
 * Having a fair taxing envoirnment (everyone gets taxed the same amount, regardless of social class).

General:


 * Ally with the countries who will grow in the near future


 * Think about the consequences and profits before starting a war
 * Help out your colonies (if you have any) because they will help out in the long run
 * Make sure choices are the reasonable and/or helpful to your own country
 * Competing with other nations has its risks and rewards.
 * Before making any big desisions, think about the effects.
 * Trade exports for more money.