First I made a list of the chores and put a dollar amount on them. For instance, harder chores were worth more. Some examples; $1.00 make your bed; $3.00 fold a basket of laundry, etc. The list also depends on the ages of your children, as you would not list cutting the grass if your children are very little. I would then post the sign on the kitchen refrigerator at their eye level. I would then assign the chores evenly as I noticed they started to fight over the higher paying chores. You can also add things like; brush your teeth, take your bath, etc. for smaller children as getting them to do these simple task can sometimes be challenging.
Next, you need to keep track of when they did them, for instance you might want to put a star next to the chore and write their name, if they did it.
Finally, at the end of the week, after they earned their money, you pay them the allowance. Now I would take my children every Friday to Borders Book Store to spend some of their money. I also would tell them to put some in a piggy bank to save some. This worked out really well because what better place to spend the money but on books. As it turned out my children all ended up in the advanced classes at school. It was a fun family outing as I would get my coffee and listen to their music as the kids would be looking for books or crafts. I hope this works for you too!