First, from the choice of tutor to consider.
You can prioritize to find the undergraduate period to give their own professional classes have taken the relevant teacher, to guide their thesis. After all, the teacher's class, teachers and students will be more or less some interaction, or the teacher, even if you do not remember you, but must have heard of your name. Mention that you have taken his class, and at the same time you can talk about some of the ideas and feelings about the class taught by the teacher, so you can also bring you and the teacher closer to each other.
Second, just from the perspective of the professional direction of the thesis.
If there is no suitable candidate among the teachers who have given you specialized courses, you can determine the teacher you want to find in the department or college according to the direction of the specialty you want to do. Before going there, it is best to carefully review the latest relevant literature, and at the same time have a preliminary conception of your dissertation. For example, the research objectives of the dissertation, the content of the research, what information is needed, etc.. All of these should be done in mind, so that you go to the tutor to facilitate communication with him, for you and the teacher's communication to lay a certain foundation of the topic.
Third, if you can not determine the direction of the thesis specialty.
If you can't figure out which research direction to do for your thesis and what topic to do. Then you can also choose 2-3 teachers in the department or college who are more interested in you, or who are closer to the research direction you want to do, as the tutors you want to apply for next. You can make a rough list of the direction you want to do your thesis, and then it is best to do some thinking and be able to list 2~3 deeper professional questions about that research direction. You can take these questions to the relevant tutor and ask the teacher for advice. In the process of asking for advice, it is likely that your mentor can be identified.
Looking for a tutor during your undergraduate studies is a very important thing that directly involves the caliber and direction of your thesis research, so it must be carefully considered. Do some homework in advance yourself, and also consult some cutting-edge literature. At the same time, you should have a relatively preliminary idea of the thesis idea, maybe your idea is wrong, but this does not matter, you can communicate with the teacher in the process of gradual modification or refinement, but can not be no idea at all.
In essence, the design of the thesis mainly depends on their own, the teacher can at most provide you with some guidance on the general direction, the specific work is still required to do their own, which must be mentally prepared in advance. As for the teacher is not familiar with, this is not the key to the problem, so do not have to be too entangled.