Sweep the pavers well, paying special attention to the corners and areas that are up against buildings, where normal buildup occurs. Examine patio pavers for stains and discolorations. If you do not note any heavy staining, clean the pavers with a simple dish liquid or mild detergent that is acid-free and water. Slosh soapy water from a bucket over the pavers and use a heavy, stiff-bristled push broom to scour the bricks. Spray pavers with clean water several times over and allow to air dry.
Consider a pressure washer for heavier soiling. Do not use one with pressures above 3,000 psi. These higher pressures can damage the brick and remove needed sand between the pavers. You may also try a high-spray pressure nozzle attached to your garden hose.
Use a light bleach and water solution with a heavy scrub brush for small patches of mold on brick. Repeat the cleansing several times until the stains are removed. If you have a heavy mold problem, scrape the affected area clean with a shovel and brush heavily to remove and loosen mold. Wash the area down well with soap and water, then follow with a bleach solution.
Prepare to use some elbow grease on oil stains. Clear oil stains will usually meld right into patio pavers and not cause staining, but for those black ugly stains, use a cloth to immediately soak up any surface oil, being careful not to smear it or rub it further into the pavers. Some clay-based kitty litters work well on oily messes, in addition to talcum powder or corn flour. After the majority of the oil is sopped up, scrub with a detergent and water several times to help remove the oil stains. For heavily affected areas, try a liquid degreaser, but always test any commercial cleaners on a small spot of the pavers before doing larger areas. Some cleaners can affect the coloring and finish of pavers.
Absorb (don't wipe) paint stains -- if they are fresh -- with a cloth towel, then rigorously scrub with soapy water and a stiff-brushed scrubber. Avoid using paint thinners, turpentine or other harsh solvent as they can force the paint more deeply into the pavers. Dried paint stains can be scraped off and any residual paint may be removed with a paint stripper.