Just follow your instincts and trust your guts.
Let people in your network know what you like and do (contacts from your non vintage business, neighbors of your parents or siblings that you are familar with, people that you meet for coffee or are in the same circles as you). In otherwords, small talk. Soon enough, when someone's family is settling an estate or someone has been hanging onto something interesting that they picked up or were given years ago, they will get on the subject with you or they will say "we should have so and so ask their ___" fill in the blank with yoru relationship to the person.
You wouldn't believe the things my dad's cousins said "if we only knew you were into that sort of thing...the things we could have given you....but we got rid of it"
Everyone has their own secret like the old Calgon commercial, but the above, that is certain, but the above is something that is more than just knowing where to go, it is being yourself and letting it come to you.
Antique clothing is more scarce to find in some respects, but once the word spreads, it will find you
Chris