Dependent and independent variables
Students tend to confuse their variables, which is a killer. Your dependent variable is what you measure/record, while your independent variable is what you change. So, if you are doing an experiment on the effect of pH levels on lactase activity, your independent variable would be the pH level (since you are changing it) and your dependent variable would be lactase activity (as you are measuring it). Also, remember to only have one dependent variable and one independent variable. All other variables should be the same throughout the experiment. Otherwise, you are doing something wrong.
Make sure you have all the equipment you need before you start, but also make sure you know how to use it safely and properly. Knowing how to use your lab equipment is crucial if you want to record accurate data, so make sure you are not doing anything wrong. Otherwise, your experiment will be invalid and all your data will be useless.
Lab safety is a basic element and everyone is more or less familiar with it. However, it can be easy to forget some things. Do not forget to wear a lab coat, goggles and even gloves if needed. Be careful with knocking things over and, basically, do not do anything reckless or stupid. The last thing you want to do is injure someone or break something.
Experiments are usually regarded as the most entertaining part of the course, but make sure you make the most of them – not only in having fun, but in developing your skills too.