In order to prepare for UPSC exam you can prefer You tube Channel given below:

Unacademy
Study for civil services

Vision IAS

Here are some preparation tips you can follow for the preparation:

Go through the previous question papers: Go through with previous year papers as it will give you an idea about the exam.

Make your own notes: It is always advisable to make notes of the related topics as you go through the books and other study material. A well drafted note solves two purposes.

Strategy for General Studies: General studies paper is equally important for Prelims and Mains examination.

History: It is a huge section & Also emphasis is given to Ancient India. A cursory glance over the medieval history is also necessary.

Geography: In this there are physical geography and maps related questions. So get yourself well-acquainted with maps with the help of a good Atlas.

General Science: It covers a major chunk of this paper and a standard guidebook can make you well-versed on the topics of general science.

Current affairs: Going through a standard newspaper daily can keep you updated on the current affairs topics.

Good Luck!