For Gujarat Board Higher Secondary School Certificate preparation you can refer to previous question papers and practice only those questions that are from the new syllabus topics.You can also practice this years model or mock test papers for better practice.You can visit the below link to know about more preparation tips and syllabus-

https://school.careers360.com/exams/gseb-hsc

You can refer to this link to download model papers-

https://school.careers360.com/download/sample-papers/gujarat-board-12th-maths-model-paper-2021