Use a small format
Date, context, a visible observation and a preparation detail are enough. Do not turn every outing into an extensive report. The notebook should be easy to use when the day was ordinary and you are ready to put the equipment away.
Save questions too
An unexplained observation may become a topic for reading later. Keep it as a question rather than naming a cause. Use a source suited to the actual subject, and preserve the link. Repeated impressions do not automatically become a documented conclusion.
Return once a month
Choose one habit to retain and one to adjust. The rest can stay as a memory. A quiet notebook grows through consistent context and honest limits, giving the next outing a clearer beginning without increasing the pressure to produce a remarkable result.