This is the simplest thing you could do. Find out whats going on in your local area. Goths tend to be accepting and open minded. Just turn up to a club or event wearing all black and your already in the goth scene. You'll pick it up as you go along (just a hint though, lay off the vampire comments!).
The gothic sense of humour is highly developed, and often leans toward the satirical. Quietly laughing at the more idiotic and less tolerant factions of society that seem to think yelling out of cars at us makes them cooler. Goths have learned to laugh at themselves and see society in a much different light. They have had to, and it is a trait most would not give up.
Goths have for the most part (not unanimously of course, but mostly) dropped all forms of prejudice. No one is afraid within the goth scene to come out as being gay, and no one has to hide their religion for fear of scorn from their peers or zealots wanting to convert them from the arms of Satan. In fact because of these facts (and the general lack of prejudice) the goth scene has a large proportion of gays/bisexuals, and followers of non-mainstream religions and views. This of course is the most important aspect of gothdom, and why most goths became goths in the first place, tolerance.