1. If you are unhappy with someone's performance then you need to do something. Letting it fester until you have no option will only make it worse.
2. Believe that there is a chance that the person you are helping could transform their performance – this will motivate you to make the effort and your faith will almost certainly have an infectious effect on them.
3. Explain the gap between what they are doing and what they need to achieve. The more specific you are the better, 'Your report on movie sponsorship did not have clear recommendations and also had four factual errors' beats 'your reports are sloppy'.
4. Discuss the gap with the person that you are coaching, and make sure that they understand it. Simply nodding agreement does not mean that they have.
5. Discover the reasons for the underperformance. Approach this with an open mind, asking questions rather than promoting your assumptions.
6. When people feel overwhelmed they can easily rush around but achieve little – relieve the pressure by helping them decide on priorities and agree deadlines for each task (or find a way to pass some of their responsibilities to someone else).
7. If the reason for underperformance is that they don't like what they are doing, help them understand how they contribute, show how you value the role ('vital to making sure that everything works smoothly' rather than 'boring admin'), and explain how excellent performance in this role could lead to greater things.
8. Decide with them what they can realistically achieve and by when. Agree to meet again to discuss progress against these goals.
9. In between meetings, use every opportunity to praise what they are doing well and to offer constructive support when things may be going awry. If you are seen to be supportive and they continue to under-perform it will be easier to take whatever action is necessary.