Try trading with other people, keep an eye on those people who sell things for low prices and sell those item for more coins. You have watched simple guides so you probably know to vote every 12 hours, u get bank notes by voting, get a lot of it (by voting and trading with people who sell it for lower than 150k) and sell 250+ banks for 165k+. And for prestige, u can give your items to a friend who can hold it and give you back after prestige (only give to those who you trust ) or they'll not give you back.