Service based businesses generally required lower investment compared to product based. But not sure in all cases. The scale of business plays important part to decide “how to start.”
Generally, based on such factors like, scale of business, investment needs (initial and long term), risks and returns, you need to decide the appropriate business structure. i.e. Proprietorship or partnership or LLP or Pvt co.
As you decide the business structure, you need to consult the professional who will help you to establish the business. If you have any query even in choosing the right structure, the professionals are at great help to guide you for the requirements and legal implications for new business registration.