If you have no idea about designing circuits, your modeling knowledge is too thin. Generally speaking, when you get the design requirements, you should have a general idea, such as some basic modules to be used in processing, such as amplification, filtering, shaping, comparison and so on. So you need to look at some application circuits on the template again, write down the common ones and use them as signal processing modules. Others, such as single chip microcomputer, sensor and special function chip, are all used by experience. Do something by yourself to broaden your horizons.
If you want to master the method of designing circuits quickly, I suggest you read the book Electronic Competition for College Students, which can provide many design ideas, and the ideas are very important.
Circuit Design of the National Undergraduate Electronic Design Competition, Huang Zhiwei, Press: Beihang University Press.