Money is important in Graveyard Keeper. You can get it by selling crops, valuable items or by completing quests. You also need money to buy items necessary for certain missions. They aren't required in crafting.
Sell collected resources
In Graveyard Keeper you'll collect a lot of resources, rocks, timber, iron, herbs, fish etc. Some of these items should be stored in chests so you won't have to collect them later.
However, some of these resources should be sold. Iron ingots can give you 60-90 coins, herbs and fish can give you over 50 coins a piece. For 50 carrots you can get several dozens of silver coins.
Repairing the graveyard and unlocking the church will enable you to celebrate a mass. Do that every Pride day to get up to several dozens of silver coins. This will also give you faith points, which makes praying one of the more lucrative activities in the game.
Sell items collected from the deceased
Maybe this solution may not be ethical, but it sure is profitable. You can extract blood, bones, organs and meat from the dead. You can sell your meat in The Dead Horse for a lot of cash. However, you must get your stamp first. You can get your stamp from the Royal services - this is the point located by the church. However, it costs 50 silver coins. You can also get it by doing a mission for Snake. When you reach the level of 30 friendship points, he will come to you and give you a stamp.
You can also sell Burial Certificates for about 90 coins a piece.