You start with a square sheet of paper. I have marked out the first creases we will be making here as well.
Short note about terminology: I will avoid using alot of the origami-words, but two I will use: Mountain fold and valley fold. Mountain folds have the crease towards you (they "rise" if you lay the paper on a table), while valley folds are the opposite. If that explanation wasn't good enough, feel free to google for a better one.
In the first part of the witch, it is important to be exact with the folds to make it fold into a good looking witch later on.
I have marked the creases you make in the active step with a white line sometimes, sometimes not. Hope you will forgive me for this.
First, fold the paper in two diagonally, creasing from B to D.
Fold the other way, so B and D meets, but only make a small crease to mark the center of the paper.
Unfold. Turn the paper over.
Fold the tip of B down to the center (E), creasing sharply from G to F. Turn over again.
Fold G in to E (in the middle, I know I forgot to mark it). Make sure the edges are even on the rest of the sheet. Crease only up until the F-G crease, not any further. Unfold. Repeat with F.
This is what your sheet should look like. The pink creases are mountains, the blue ones valleys.
Now comes a part I am not able to explain very well. Make five shourt creases in the B-triangle, like shown below. Basically you fold the tips in along the creases, paralell, and then make a short crease inbetween the edge triangles. You might have to try a couple of times to make it look good, but it's fairly simple when you get it.
If you did the five creases above right, it should look like this when you press it flat.
Then fold the A/C flaps behind, like this.
Turned over this is what it looks like.
Fold it in two along the B/D line, collapsing the B-point at an angle. This is what it should look like:
Fold the J corner up, edge to edge with the diagonal midline. Unfold and repeat with I.
Repeat the fold above, but but the J corner behind like below. You make no new creases in this move, though you have to reverse a formerly made crease.
Now you should have this shape!
Grap the long triangle and reverse it to the front. Try to make the upper edge touch approximately upon the corner of crease we just made when folding up J.
It is going to become the broomstick.
Make it narrower by folding in on both sides like this:
Resulting in something like this! Almost there.
The two points that used to be A and C are hanging down in the back. Fold these in. You have to partway fold the edge in front of it with it, flattening it down like below. I hope that makes sense, with the help of the photo.
You should have this:
And the last step: Making arms.
Make a small fold like this in both sides.
And you are done!