Recommend several books: Special Topics on Architecture and Hand-painted Performance Design, and Hand-painted Performance of Architectural Landscape Design by Guo Zhu. Conception and Expression (Chen Xinsheng) (Machinery Industry Press) Planning Hand-painted Expression (WU GANG) (Tongji University Press)

Practice hand painting. In fact, most books have methods of introduction. The key lies in your own practice and understanding. If you can communicate and discuss with the teacher during the internship, it will be more helpful for you to participate in the postgraduate entrance examination for quick design in the future.