Firstly you want to get your approval rating to maximum and keep it near there. 10% of the coffers is spent each day up to a maximum of 50K (Throne of Miscellania) or 75K (Royal Trouble) on the items you put the workers on, effectively buying you those items at typically far below market prices. So if you want the most stuff you'd want to put in at least 500k or 750k, preferably more if you don't want to check on it every day.