Refers to the very first stage or moment of something, often used in phrases like とっつきから (from the very beginning).
I stumbled right from the start.
The beginning of this job is crucial.
noun which may take the genitive case particle 'no'
first impression; initial approach; first thing one encounters
Describes the initial feel or accessibility of something, especially a person, task, or place. Often used with いい/悪い.
He is an approachable person.
This book is technical and hard to get into.
affability; approachability
Specifically refers to a person's friendly, easy-to-approach nature. Overlaps with sense 2 but focuses on personality.
Her affability eased the tension in the meeting.