IMO rubbing alcohol is better for cleaning a simple glass piece like this. It's a solvent and will remove the vapor residue. And the more often you clean it the easier it'll be. Cleaning it immediately after use, while the residue is still heated, makes it even easier.
And please pick a descriptive thread title. A title like 'Please' (changed to reflect your need) says nothing about the topic. Also, Ask FC, where your thread has been relocated, is the place for questions like this. General Vaporization is not for questions on specific models.