Your lab report should be organized, thorough and detailed. With this in mind you should write as concisely as possible . Before you put in a statement, a figure, or a table, ask yourself if it is adding to the quality of the paper. If it is not, leave it out. A title should be descriptive and tells the reader what the paper is about.
Abstracts are necessary for quick scanning of scientific literature when researching a topic.
The abstract should be intelligible without reference to the rest of the paper. It is usually easier to write the abstract after you have finished the rest of the paper. An introduction should let the reader know what you are doing in the experiment and why you are doing it. You will therefore need to review what is known in the subject area and how your experiment will contribute to what is known. A well written introduction, while reviewing the literature, should draw the reader's attention to the purpose of the experiment, resulting in a specific statement of the hypothesis.