You might want to try this link. Has a protocol for precipitating filamentous phages.

http://www.abdesignlabs.com/technical-resources/bacteriophage-preparation/

TBS (or PBS) is just used to remove the precipitating agent (PEG) and resolubilize phages before the second precipitation step. Low temperatures increase the  precipitation efficiency, as higher temperatures tend to promote solubilization. 

Thanks Gertrudis Rojas, I have a follow-up question: what would the second precipitation step be? A second time PEG/NaCl or do you prefer something else?

Yes, I usually do a second precipitation step with PEG/NaCl. As this second precipitation is done in smaller volumes, the quick apperance of a white precipitate is clearly seen, so you can judge the success of your phage production.