To be able to speak "si" and "shi" clearly is certainly great. But if you can't, there's no need to sweat too much about it.
Many Chinese people can't. People from the south, including Shanghai, Taiwan, and Guangdong, they can't different "si" and "shi" very clearly in their speech. But that doesn't stop people are communicating with one another in Putonghua. In fact, I enjoy speaking to Taiwan people, and I quite like their soft accent.
Therefore, context is far more important than constant drills of "zi, ci, si, zhi, chi, shi".
april
