Then, do not simply look for a famous mathematics or history professor, for example; look for someone who has extensive experience studying your specific topic of interest. No matter how intelligent and renowned advisers are, the less familiar they are with your specific topic, the more effort you will have to expend teaching them about it. An adviser with experience in a field slightly different from that of your intended area of study may offer a unique perspective, may ask helpful questions, and may inadvertently require clarity in presentation. But this will inevitably cost time.
Find a good advisor who is well-versed in your specific topic of interest to minimize the amount of time you need to spend teaching them about your specific area.