If someone is uncertain about the permissibility of a financial transaction involving interest (*riba*) or speculation (*gharar*), they should take these steps:

1. **Seek Knowledge**: Research Islamic finance principles related to interest, speculation, and permissible investments.

2. **Consult a Scholar**: Reach out to a knowledgeable Islamic scholar or financial expert specializing in Islamic finance for guidance.

3. **Use Caution**: If the transaction’s permissibility remains unclear, consider following the principle of avoiding doubtful matters (*wara’*), as this approach aligns with Islamic ethics by prioritizing caution and avoiding potential harm.

If still unsure, opting for an alternative, clearly halal option may provide peace of mind.