First of all, you should give a brief introduction of the project. Tell your reader what was the basic purpose of that project and what forced you to initiate it. You must engage them by telling something that can be interesting for them. However, do not reveal much as your aim is to intrigue the reader.
Now, when they have got the basic idea about your project, there is no harm in giving them a taste of your report. Mention few important questions that have been answered in this report. You can reveal a few of your findings but keep your description short.
Your next step will be to discuss the genesis of the work to follow. If there is any external input such as surveys, group discussion or even your own observation then do mention it. Make it as powerful as you can otherwise you might lose their attention. Say or reveal something that is hitting them directly and making an impact.
Sometimes, you can also mention for whom the project is specifically targeted. In this case, you will have to explain why you decided to initiate this project for a certain group of people. However, you should write this segment very tactfully as you do not want to make this report irrelevant for others.
In the next section of the preface, you will talk about the organisation of your project report. If you think that few of your readers can skip some sections or chapters of the report then guide them properly. Similarly, you should also justify the order of chapters.
Discuss your sources and mention the work done by them. You will discuss from where you started the journey and reached at a conclusion. Give your personal opinion about the project.
In the end, you will give thanks and acknowledgments to those who helped you to compile this report.