Prospective borrowers can start by checking personal loan offers from banks or NBFCs where they already have deposit, loan, or credit card accounts. This is because most lenders offer preferential interest rates to their existing customers. Additionally, they can visit online financial marketplaces like Paisabazaar.com to compare personal loan interest rates and other loan features offered by various banks and NBFCs. Then, they should use the Personal Loan APR Calculator to compare the actual borrowing cost after factoring in the interest rates, processing fees, login fees, etc.