Find out who represents your government at the FATF plenary (likely to be the Ministry of Finance) and request a meeting. If your country is not a member of FATF find out who in government is the contact for the FATF regional body. A list of FATF members and regional bodies is here.
Be aware of when your country is up for an FATF evaluation. Form a coalition to advocate the cause of a free and fully-functioning civil society space.
Learn from civil society in countries that have gone through the mutual evaluation process.
Keep tabs on and highlight rules/regulations/laws that are, either directly or indirectly, affecting your ability to function effectively.
The FATF has now made it possible for civil society and other interested stakeholders to share and provide submissions ahead of a country's Mutual Evaluation process. Please see here for further details, including for where and when these submissions can be made and what format they should take. Do keep in mind that all submissions will be shared with the country being assessed and that the source of the information will be identified. The deadline for submission is two months prior to the scheduled onsite visit.
Case Study (2017) on US Nonprofit Organizations and the FATF Mutual Evaluation Process 2015-16