Set individual 'Gold per Village' for each side. Give handicap to friends-beginners (so that the game would be more challenging), or AI.
Player1 gold:  income: 
Player2 gold:  income: [+1] <-------
Player4 gold:  income: 
Player3 gold:  income: 
With this add-on, _each village_ of Player2 will provide 1 additional gold per turn. (Compare this to constant +1 as per default rules.)
Because the income bonus depends on owned villages, it scales with map size (making it suitable even for large maps).
Note: this add-on has no effect if you don't set any handicaps.