Postgresql Cost-Based Vacuum Delay parameters How to set the these parameters on postgresql.conf ? 
What I should consider while setting them? 
What should I monitor?

#vacuum_cost_delay = 0ms                
#vacuum_cost_page_hit = 1                
#vacuum_cost_page_miss = 10             
#vacuum_cost_page_dirty = 20            
#vacuum_cost_limit = 200    


is there any good tutorial or example?
The postgres docs are the best place to start