Gave me the syllabus of nts test for admission in tefl diploma in allama iqbal open university
You may consider taking up classes from an institute like ACE as they provide good coaching for NTSE exams.
NTSE does not have any prescribed syllabus. For the first stage, you should be thorough with the state syllabus books and ncert books of classes 6-8 and almost perfect in Mental ability. For mental ability, Tata Mcgraw Hills and Arihant are good books.