Nothing really, just you, a nice peaceful place and a little imagination. It is nice to have all the bits and bobs though, and you'll probably want to have them to help you to focus. Don't go mad, however, and buy all sorts of those wonderful things that you see in your local occult shop or catalogue; most people do. I did, and it was good fun, but later on you come to realise that you really didn't need so much stuff after all. They do look good on your altar though.
Altar
You can have a permanent altar if you have the room and privacy, but most of us don't. I use a small desk on wheels, which I can move about easily and I keep my things in a small cupboard out of the way. I also use a piece of slate, especially if I'm doing stuff outside; it stops the candle wax getting onto the grass and I would never, ever stick a candle onto a rock in a stone circle.
Collect
things for your altar. You will come across lots of things on your travels,
things from nature, like stones, feathers, shell on the beach. You can
change your altar decorations along with the seasons, go out for a walk
just before the sabbats, go with an open mind, don't look for specific
things, you may be surprised at what you will find.
Athame
I bought
one from a great occult place in Edinburgh called The Wyrd Shop. It is
very plain with no decoration al all on it. You can however
buy a double
edged knife from a general store and decorate the handle with paint or
use polymer clay, which comes in lots of great colours. The problem with
buying a second hand knife is that you don't know what it has been used
for, killing animals perhaps. Unless you know its history, don't touch
it. Remember to cleanse your athame before you use it.
Wand
Since
I still haven't found a piece of tree that I can make into a wand, I made
one out of polymer clay. It's not very natural, but it seems to work for
me, and that's what matters I suppose. It is blue with yin/yang symbols
and pentagrams on it and has a quartz crystal on the tip. I'll keep looking
for my bit of tree lying on the grass, I'm sure that the right one will
come along.
Pentacle
I have
a small pentacle wall plaque made from plaster, that I got on one of my
witchie spending sprees, I love it, but I need one to lay flat on my altar.
I think I hear the polymer clay calling again. I suppose I could try and
make one from a piece of wood, I'll see how it goes.
Staff
I use a staff instead of a broom, or I will when I've finished it. I couldn't find a suitable piece of tree to work with, so i bought a thick piece of wooden dowling from a DIY shop in town. I've painted it green and put on a handgrip, by wrapping some faux suede around and gluing it on.