Hello,
For 8th Standard scholorship preparation, Thoroughly study class 7 and 8 textbooks for all subjects. Try to strengthen the core subjects which are Mathematics, Science, Social science, English. Practise mental ability(MAT) and sample papers. Revise your learnings.
To get more details for 8th Standard scholarship, Kindly check the following link.
https://school.careers360.com/articles/scholarships-for-class-8-students

I hope this helps you.