There's no specific aim for how you should distribute your power tokens. They are an indicator of the dynamics of a power struggle but save for a few events that refer to the "leading faction" they have little mechanical bearing, so you are free to deal with them as you wish. It's just important to note that gaining / losing power may move more than one power token.
Also as a note: when a resource is removed, 2 power tokens need to be removed from the city as well. Probably from the resource on the map but also from factions, if some had been moved off.