Design and implementation of simple symmetric cryptographic protocols is a greater challenge than commonly believed. Text books, which mostly focus on the theoretical aspects of cryptographic primitives, are only of little help concerning the avoidance of plain and subtle weaknesses. The paper "Applying Symmetric Encryption" tries to close this gap. It addresses an audience with basic understanding of cryptographic terminology such as block ciphers. It summarizes potential vulnerabilities in basic symmetric encryption schemes based on very recent works.