Ask HN: How do you self-assess?

I recently applied to a job from a HN monthly post and I was told that the company is looking for more experienced people. That made me think about metrics for measuring experience. Which made me ask myself questions on self-assessment. I realised that I might lack the skill.

Therefore, I'm turning to the HN community to see how that goes here.

Note: I'm mostly referring to technical self-assessment, but I'm curious about self-assessment in other domains too (specifically in those that have a more fluid definition of "quality").