[header] How to clean a glass pipe [title] Remove any loose gunk from the pipe. [step] Hold the pipe upside down and gently tap to remove any remaining particles. Then use a pipe cleaner, cotton swab, mechanical pencil, needle, or similarly thin object to remove any large, easily dislodged bits of resin you can reach. 
[substeps] Don't risk breaking the pipe to get at tough spots, as you only need to get anything big and easy to reach off now. This will help the alcohol clean the rest of the pipe faster.