Considering you are done with your syllabus and going to devote rest 1 month in your revision, so you can go through below tips for the same -
1. Choose subject/topic according to weightage of marks allotted in BITSAT.
2. Set a study plan and stick to it. Divide your preparation in several steps and complete them one by one.
3. Prepare, master and revise. Practise as many online and mock papers as you can.
4. Learn the art of Time Management through online practice papers.

Hope this helps!!!

Good Luck!!!