Separate what happened from what you make of it
A personal note may contain an observation and an interpretation, but they should remain distinguishable. Three people left before the session ended records an event. They disliked the session proposes an explanation. Labelling the difference keeps later readers from mistaking your inference for an observed fact.
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Give each kind of statement its own place
After an event, you write that several participants left early because the topic was too difficult. You observed the departures, but unless they explained their reasons, the cause remains an interpretation.
Separate observation from interpretation in the note. You can record what happened first, then add possible explanations and any questions that remain.
This preserves the useful idea without making it stronger than the available information. Later evidence may support one interpretation or suggest a different one.
The distinction also helps when rereading your own notes. A sentence written quickly can lose its original uncertainty over time. Clear labels allow a hypothesis to remain a hypothesis until something more than repetition supports it.