I think one of the best and the most renowned place for overall preparation as well as subject wise preparation for UPSC exams is the Chanakya IAS academy. Many people from all over the country come to get tuition at this place. It is an extremely professional establishment and goes through the procedure in a very systematic manner.
However, if you need more detailed study plan and personalized guidance then it is best to get a private tutor who can guide you in every step and plan in the study based on your strength and weaknesses. Ideally this is more beneficial for the student but finding the perfect guide can be quite a difficult task. if you somehow manage to find a good teacher then you can also save a lot of money. With this you can buy huge number of
UPSC test series which will help you prepare for the actual test with wide variety of possible questions. for me personally the second option looks much better as there is nothing like personal guidance from a well educated person.