So many other factors impact your sun sign -- house, aspects, Ascendant, Moon, etc.  Not sure you can advise without considering those.  In my case -- Aries Sun, Cap Rising, Virgo Moon -- "Examine in depth before you leap!"

Sun in Aquarius ♒️. I would say to my young self “Do not take it personally when others don’t respond kindly . We don’t know what they’re going through. You cannot expect to be friends with the whole world”.

What a great question. "Keep it clean," maybe.  "Relatively."

Sun in Scorpio (along with a stellium of 4 more Scorpio planets next to it) Cancer rising Taurus moon.

It does hurt that bad, but you have to find a way to detach. Your whole life will be easier if you can learn to detach and let go.