A tip to remember is that accuracy depends upon systematic error while precision depends upon random error. Furthermore, systematic error has a constant sign and magnitude and random error has a varying sign and magnitude. When you're asked in the examination to pick out the errors and then provide symmetric improvements, keep in mind which factor is variable and why. This is your random error. DO NOT ever assume a systematic error, because that way you're either implying that you're too big a goof to work a way around the systematic error. Quantities like reaction time, temperature (was the AC on when the practical started, but not later? This is reported by the center so use it to your advantage, but try to remain focused), distance, measurement of extreme position (parallax error?), etc. Good luck!