Read your laboratory manual before attending the lab. At the least you should know what the aim of the experiment is.
Read the appropriate literature before the lab. For example, if you are doing a lab on ECG’s, then know what an ECG is and what the waveforms represent.
Try to understand the lab during laboratory time. Do you know what it is that you are looking at on your computer screen? If you don’t - ASK! Do not take the attitude - “I will just get the results now and figure it out later” because believe me - you won’t.
Write up your results and discussion sections first. These are the most important sections for your learning and will help you focus on what is relevant for your introduction.
Look at each set of results and try to explain them using your own knowledge. If you can’t explain them then read a text book (remember to use the index - it doesn’t help to read the 3 chapters on the topic). If you are still at a loss, make an appointment with the tutors.