Beginners,doing multiple modifications at once......

I don't know if anyone has mentioned this yet but I have seen it get a lot of racers into trouble. Change one thing and go to the track and see what it did. If you make multiple adjustments at one time then your not going to know if one of them helped or hurt you. I made the mistake of putting in a new rear end and changing the carb and running it. My times barley dropped but I couldn't tell if one thing was hurting or helping!