This is a very simple circuit for matching transistors. I would recomend the use of a 4 1/2 digit voltmeter. Idealy, you need 0.1mV resolution. Also, do not handle the transistors with your fingers. I pick them up by the leads with a pair for pliers. If you heat them up with your fingers, you will through the reading off. What I did is I built the circuit on one of the breadboard things. I put in a transistor, measure the voltage at both currents, write them down on a piece of paper, and then tape the transistor next to the readings.
Also, you need to do this when the temperature is
not chaning very fast. I generally do it early in the morning.