"The Conversation" magazine tells us five ways

https://theconversation.com/five-ways-to-improve-the-global-voluntary-carbon-credit-markets-232119

The voluntary carbon markets were established to allow companies to offset their emissions by buying and selling carbon credits, which represent promises to offset greenhouse gas emissions through future emission avoidance or atmospheric extraction. Whilst these markets currently channel billions of pounds annually and are expected to grow significantly, they have faced criticism for enabling greenwashing and failing to produce real carbon emission reductions. Despite these challenges, experts believe that voluntary carbon markets remain an essential part of global efforts to reduce emissions, provided they are implemented properly.

To restore trust in voluntary carbon markets, five key principles have been proposed: increasing transparency in all aspects of the market, improving accreditation through standardisation and quality-based fee structures, ensuring projects do no harm and benefit local communities, focusing on high-quality credits that prioritise carbon removal over emissions reduction, and garnering more international support through regulation and governance principles. By adhering to these principles, voluntary carbon markets could potentially mobilise significant private funding for emission reduction projects and play a crucial role in combating the climate crisis.