Set up a circuit as shown in the diagram below.
Add the component to be tested in the space between the circular terminals.
Record the current and voltage.
Slowly alter the variable resistor to increase the current and read off the voltage.
Aim for a minimum of ten readings over the full range of the variable resistor.
Repeat the whole process twice more and calculate an average.
Plot a graph of the current and voltage ensuring that the current in plotted on the X-axis.
The gradient of your graph is equal to the resistance of the component.
You can turn your component around to test the effect of changing the current passing through it in the opposite direction.
Temperature also has an affect on the resistance of a component and some components will heat significantly when in use.