The most straightforward and profitable business idea that I have come across is bookkeeping, accounting, tax preparation, and payroll services. According to a 2017 Sageworks report, these businesses have a net profit margin of 184%. These services are always in demand, and businesses of all sizes need them to stay compliant with regulations and keep track of their finances. Additionally, starting a business in this field does not require a significant investment, as it mainly involves providing services to clients rather than producing a physical product. Another profitable business idea is pet care services, such as dog walking or pet sitting. With more people owning pets than ever before, the demand for these services is high, and they can be started with little to no upfront cost. Pet care services also allow entrepreneurs to combine their love for animals with a profitable business venture.