What does the bottom-up approach entail? Review past projects that are similar to the current project to get an idea of what the project could involve. Think about all the parts of a project from the beginning to the end that have an associated cost, and add all of that together. Establish the main objectives of a project and keep them within a reasonable framework to ensure the project makes financial sense. Gather insights from experts who worked on a similar project in the past and use their knowledge as a resource