Where to begin?

How do I get started?

I have a crappy car, and no money to spare. I just want to take it out and drive it around some cones and see what it can do.

I don't really want to join up with (and pay dues to) the SCCA or whatever before I have a better car and more time to devote to it and to racing.

What do I need in my street car? I need a helmet at least, right? Any other specific safety equipment?

you don't have to have anything. there are usually helmets available to use. no other safety equipment needed that i know of. i don't know if you have to be part of a club to participate but i wouldn't think you would.

You don't have to be a member of the SCCA to race all you will need is a car that can pass tech and some money to pay the entrance fee usually $20-$30.
Here is a link to a site that can answer most of your questions. http://www.conecrazy.com/
Fallow the links to solo2 and find your regional info.
Have fun.

The whole point of Autocross is that its "come as you are" racing. Some people ask "What mods should I make before I show up?". The answer is NONE! You'll have a much better idea of what mods are useful after you get a chance to talk to the experts.

Autocrossers are generally friendly, and almost always very helpful. As for joining, the main reason to join your local SCCA chapter is cheaper admission to the events.

Go - have fun. Only start worrying if the speed bug bites you.

I always tell new autocrossers that the first thing that they need to "mod" is themselves. Don't make any modifications to your car until you feel that you have extracted every last bit of performance out of your car as it is. You will be surprised at how much your car can handle. Make the driver better first, you will go faster that way. Anyway, by the time you are superfast in your current car you will be itching to upgrade to something with more power and better handling.

Just keep the car you got to practice with. once you feel up to it then thats when you start getting serious about things and moving farther. I can only help when i say...PRACTICE.