Tips on properly playing a Malkavian
Many players make the mistake of playing the Malkavians as comic relief or clownish vampires. All too often are Malkavians given ridiculous derangements such as the need to speak to a sock puppet.
The Malkavians, as written in White Wolf's source material, are to be terrifying and bloody. Justin Achilli, the developer of Vampire: The Masquerade, has written at length on the subject of how Malkavians are intended to be scary.
One of the tales written in their books talks about how Malkav, the progenitor of the clan, was blood thirsty and sadistic when Caine, the original vampire, cursed him with insanity. He did so with the intention that he would be forever alone because he would instill fear into the hearts of anyone he encountered.
An important aspect of any Malkavian is the particular brand of insanity s/he has. When creating a character, the player should do a little research into what sort of debilitating mental problems there are and choose one that the player feels s/he can accurately portray. This is intended to be a hindrance, so it should be somewhat crippling and inconvenient for the character. Remember that the derangement is the primary aspect of what a Malkavian is, so ensure that s/he has a good one that will instill fear in the other characters.
Avoid playing concepts that would make people laugh. Concepts such as mimes, people with sock puppets, or people who only communicate with Elvis lyrics.