Download SDK
The first thing to do is download the Symbian OS C++ SDK. Which SDK to download? There are several SDKs depending on the UI platforms of the phones.
Download IDE
Another question that usually comes up from developers is "Which IDE to use?" Once again, there are several IDEs supporting Symbian OS C++.
Buy Books
There have been many concerns about the quality of SDK documentation, which is not good enough. That’s why I would recommend buying one of Symbian OS C++ books
Technical Articles, Sample Codes and Forum Discussion
Sometimes books are not enough, so you may want to read some technical articles about Symbian OS C++ as well. There are several good sources
Source: Forum Nokia
All you developers get cracking!