Managing self-doubt -

Pay attention to the evidence that you're getting from the world. Are you getting clear repeated information from the stakeholders that matter to you that you need more  preparation?

Listen to actual feedback rather than you're inner critic.

Most people never get the that stage of even asking their intended audience for feedback - they make up a story in their head and it's usually a convenient story that allows them to hide a little bit - that they need to do more preparatory work.

Self-doubt : Is it coming to you in real information and evidence from the outside world.

Creating a story that is more about fear than the external thing itself.