Decide which activities are the most important and do them when you are the most rested. This will probably be in the morning. Also build in regular rest breaks throughout the day, and plan to do those things that require the greatest effort when you are well rested. Limit what vou do. Don't try to do as many things as you did before your head injury.
Many people find their communication abilities deteriorate as they become tired.
Use this as a signal to rest or to take a break from what you are doing. Evaluate what a job requires. Plan how long it will take you to complete a job. This will reduce the stress associated with unrealistic time pressures. Talk to yourself before you start the task.