I pick an odd version of their name, or name them with their consent.
I was a Joshua for years, but I DESPISE being called Josh, it isn't my name, it is unaesthetic, and to top it all off, it's popular enough that I got stuck with "Josh M." for years.
Then I decided to go by Shua (sh-wah), which was fun, and suited me better. I now inform every Josh I meet that they could be a Shua if they wanted. I also check for cool middle names, but Lee doesn't suit me as well so I stuck with Shua for years.
Then my girlfriend broke a rule I have (NO NICKNAMES, EVER), and renamed me Max. I prefer it, so I adopted it full time. Will be legally changing my name someday, but I already sign it, and use it for all other purposes, because I don't accept a court or arbitrary group representing lines on a made-up map (a government) to have any more validity in deciding what name I use than I myself have.
Her name is now Bunny, incidentally, cause the name she was given with didn't fit as well, and that's who she is to me now. Max and Bunny, or Joshua and Courtney... obvious choice upon meeting us, I think.
Oh, I hate being called sir, because I don't use the term myself. If I wanted to be polite, I'll call you Mr., or Mr. (your last name) in extreme cases, which would be rare... I do refer to Professors as Prof. (name), or Dr. (name) after checking which they prefer, only going with other names if they ask... because well, they did earn the title.
Unlike, oddly enough, cops, who I simply address in a neutral social fashion. No terms of deference or respect, simply speak to them as if they were some oddly uncouth person who interrupted you, works well as they are somewhat put at ease by the assumption that I have no reason to treat them as if I am a criminal, whether I'm technically breaking a law or not. They're just some guy with odd clothes and a gun to me, I've had a few of them comment on that... if they managed to catch me, which was rarely.
I do refer to women as Miss, or Milady, or Young Lady, which is apparently quite charming... even when she's clearly 60 to 70 years old, because they all giggle and pinch my arms.