To easiest way for this is to start a Grand Campaign on the lowest difficulty as the Dwarves. Dwarves have very high incomes with a lot of income buildings. Keep occupying settlements with a balance between income and other buildings. Don't forget that armies will require upkeep, that'll lower the gold per turn.
It'll probably come naturally during the Grand Campaign. At the end of mine I had an income of almost 44k per turn, with 6 armies full of units.