Hi there,
Do's:
Take your time.
Change over customers in blocks.
Clean frames first then glass.
Make sure you RINSE thoroughly.
Check your TDS reading daily.
Keep on top of resin and flushing out RO units.
Keep a few spares, pressure switches, connectors etc....
Dont's:
Rush.
Clean the vents above windows.
Hold back with water when rinsing.
Expect no call backs initially.
Try to run before you can walk
Otherwise,
good luck,
Trev