C. We do not use a reflexive pronoun after verbs which describe things people (e.g. feel, relax, concentrate, meet, etc.), and usually do for themselves (e.g. wash, shave, dress, etc.)
C1. We only use reflexives with these verbs for emphasis.
C2. We use personal pronouns, not reflexives, after prepositions of place.
C3. after with when it means ‘accompanied by’.
D. We can say ‘(a friend) of mine/ yours/ his/ hers/ ours/ theirs’.
D1. In the same way we say ‘(a friend) of my sister’s/ (a friend) of John’s’.
D2. use my/ your/ his/ her/ its/ our/ their before own.
D3. My own ~/ your own ~ etc. = something that is only mine/ yours, not shared or borrowed.
D4. by myself and on my own both mean ‘alone‘