Honestly the biggest restriction most people probably have is lack of space. I'm not even allowed a grill at most apartments, let alone a fire hot enough to work steel. I've been waiting 15+ years to start at this point, so a few more until I can buy/rent a house won't kill me.
There may be a forge in your area that you can rent time at. Here's a place on the edge of Boston that offers both classes and an "open smithy" for working on your own stuff: http://www.prospecthillforge.com/ (if nothing else, click for the nostalgic Web 1.0 design)
Went to this place a few months ago taking one of the intro classes, the guy that ran the class is super nice and has a very fun teaching style. You man the forges in pairs so it's a good idea to take the class with a friend.
There's a ton of metalwork techniques that don't require heat at all. Some can even be done with only a few hand tools. I started with Chainmail when I was 14. If you're not coiling the wire to make the rings yourself, you can make a ton of things with only two pairs of pliers.
I highly recommend one of those pairs be parallel pliers.
