The hows and whys on helping overcome the Tip-of-the-Tongue effect (PDF):
One of the most fascinating things about the tip-of-the-tongue state, is that it demonstrates how sometimes we know that we know something, without actually being able to recall it. This is part of what psychologists call ‘metacognition’, which allows us to realise when we should keep trying, despite the fact our memories might be failing us at a particular moment.
When a tip-of-tongue state is encountered, it is common that people focus on the few relevant things that are easily remembered, in the hope that the elusive fact will pop into mind. A more successful technique is to try and recall as much information about the topic as possible, no matter how loosely it is related.