How do i clean the hp printer's in order to get a clean and darker print?

Print quality depends on cartridge health condition only, especially in inkjet printers.*Print head clogging: Usually white horizontal lines in print outs due to print head nozzles are clogged. Printer it self having self cleaning mechanism to clean the nozzles while printing & powering on..And "clean nozzles" option also designed in printer drivers for cleaning. And last option is manual cleaning. Alcohol is good solvent & best for cleaning the nozzles,use cotton or ear buds to swab on the surface of the nozzles with alcohol gently.. You will get good quality print outs if cartridges are in good condition..(see the snap shots)Other parts to clean: Encoder,disc encoder, service station & rollers needs to clean periodically to avoid malfunctions & paper jams.* Encoder's malfunctions: If any vertical or horizontal crooked print outs observed, clean both encoders needs to clean.. (see snap shot for encoders)*Service station malfunctions: If any carriage jams observed in service station, remove & clean it ..(see the snap shot)*Rollers malfunctions: If media is not picking up properly it causes jamming error,clean or replace the rollers..