This is really simple, basic soap.  If you're interested in something fancy, or pretty, or scented, there are a lot of good books on how to do it - this gives the basics, and if you want to do more, it should get you started.  This will produce a decent, inexpensive soap.

Equipment:  2 quart glass container or a enamel on steel saucepan, 10-12 quart enamel on steel pot, wooden spoon, candy thermometer, molds (wood is idea, but I've used cardboard boxes lined with wax paper quite successfully), newspapers to cover your work surface.

Warning:  Aluminum and lye don't mix - do not use aluminum containers or utensils for soap making.

Getting Started:

Do these in the order given - the timing will work better that way.

1)  Heat the fat - 95-98 degrees.

2)  Spread the newspapers on your work area - this is important, because both the lye-water mixture and the newly mixed soap are quite capable of removing the finish from your table.

3)  Put cold water into your glass container or saucepan - slowly stir in the lye.  This will immediately heat up to over 200 degrees, so be careful with it.  Set it aside to cool (you can stand it in a container of cold water if you wish).

4)  When the lye has cooled to 95-98 degrees, remove the fat from the heat, stir it, and slowly add the lye while stirring.  It will become opaque and dark, and then begin to lighten.  When it is the consistency of sour cream, and a drop of the mixture will stay briefly on the surface, it is ready.

(If it doesn't begin to thicken, don't panic - reheat it and try again).

5)  Carefully pour into molds, cover with a blanket for 24 hours, then remove from mold and allow it to stand uncovered for 3 or 4 weeks.  If you touch your tongue to the soap and it stings, then it has not completely cured.

What To Use:

You can use rendered fat, drippings, oil, or any combination (please see Drippings and Rendering).  Most vegetable oils don't make a soap with a lot of lather (olive oil being the exception) and tallow (beef fat) makes the best all purpose soap.  You can keep your drippings and trimmings, you can usually buy beef fat for a decent price from a butcher, or you can use oil, or a mixture of the three.  That said, I use drippings and whatever mixture of fats that happens to be still produces a useable soap.  The basic soap should be:

6 lbs fat
2 1/2 pints water
13 oz of lye (you can usually find this with the drain cleaners in the grocery store - I like Red Devil)

If you want to try a small batch:

1 cup fat
1/2 cup cold water
2 heaping teaspoons of lye

I've always used the 95-98 degrees, but here are some alternate temperatures for specific fats:

Tallow (beef)     fat 125 degrees        lye 93 degrees
Lard (pork)    fat 83 degrees        lye 73 degrees
Half each    fat 105 degrees        lye 83 degrees