Flowcharts can be very useful for a technical writer. If you';re working on a complex process, a flowchart can show you the various steps involved in that process. For example, you could be working on a manual on how to troubleshoot the Autopilot Flight Director system for the Boeing 747 aircraft. There are various steps involved in troubleshooting this system. Each step has multiple sub_steps. By creating a flowchart, you can quickly see which step takes place at what stage in the process.
After deciding on the points you want to make in your upcoming presentation, you need to figure out how to support those points. For example, if your point is that your company has the largest market share in the industry, quote the research (hopefully done by a third party) that says so. This applies to both business presentations and educational presentations. The support you provide for your message is essential for an effective presentation.