I guess technically this would be selling a service instead of a good.

I was going through the 4 combinations of balanced two-line entries, based on the accounting equation, to show how it helps when thinking through how to record something.

If you get into more than two lines, then yup selling a good would be

  +Asset -Asset +Income

or if you include sales tax and son shipping costs:

  +Asset -Asset +Liability +Income +Expense

Using an updated accounting equation and negative numbers is a lot more intuitive than credits and debits. In this larger example it tells you:

  Cash Asset - COGS Asset - Tax Liability = Sales Income - Shipping Expense

It tells you what types of accounts balance, with a syntax that matches your intuitions: more asset = good, less asset = bad, more expense = bad, less expense = good.