I started doing double-entry bookkeeping with GnuCash to keep track of my personal finances, down to the penny. I have as assets my bank account and "cash in wallet", and many expense accounts for food, gas, water, electricity, clothes, transport/commuting and so on.
In the context of double-entry bookkeeping in GnuCash, how can I reflect gaining money by selling an item, for example selling a camera on Craigslist? Or that I gained money by selling a commuting ticket or gift card that I no longer use?
For the time being, I made an account called "items sold" of type Income, but I am not sure if this is the right or best way to do it.
Somehow I feel that by selling something, some type of asset should decrease and Income should increase. On the other hand, things like cameras, gift cards and whatever are not money, so I'm not sure if they should have their own account.
How do I properly double-entry bookkeep this?