Understand the DNA of mens fashion by learning the key components of each part. Of course, you can always start from here.
Educate yourself about modern styles. Especially for young or young at heart men, pick up the latest mens magazine and see whats going on in the world out there. What are the latest fashions? Crazes? Weird things people are wearing out there?
However, don't jump straight into the fashion magazines without first knowing the fundementals. Your fashion sense will appear flaky and unrealiable, always chasing after the next big thing.
When you are grounded in the solidity of classic styles, you will then know what are the little subtle tweaks to bring out your own permament, personal style.
Open your eyes bigger and start looking out for smartly dressed people around. Ask around your friends, family and co-workers if they have any reputable tailor to introduce or how did they choose a tailor.
When you learn to spot strangers wearing tailored shirts you admire, typically those with unique designs or are unusually well fitting, pluck up the courage to go ask them where did they do it.
You might want to practise with you spouse at home. Walk up to her, and say "Hi there, I noticed your shirt has such exceptional fit and style. It looks great. Just curious, is it tailor made?"
Once you get used to saying it, its easier to say that to strangers.
It might sound psychotic and make you seem like a stalker, but I do think it feels rather flattering for the target. Or at least try to make it flattering for him.
Have an idea of how much the tailor would cost before visiting. No point going to a tailor that you love, but cost twice as expensive as your budget.
Be realistic. Call first and ask for a ball park figure before you choose a tailor. Most tailors would be happy to provide it, as they also dont want to waste their time.