The application form isn't too bad compared to others that are out there as they are pretty standard questions. The numerical and verbal reasoning tests are okay if you practice a little bit before. Doing the shl practice tests help because shl direct provide the tests for deloitte.
The phone interview is pretty simple, its just to make sure that you have a not terrible phone manner. Just prepare answers for things like why deloitte, and you should be fine. Its very short.
Where I faltered was the first round interview. In this, I would say ensure that you are professional at all times and that you have competency answers prepared beforehand.