First get all types of longbows or if you
are short of cash a crossbow. Then buy 500 bronze arrows and 500 iron arrows or 1000 bronze crossbow bolts (if you are using crossbow) Start out your training in lumbridge at the chickens south of the castle. Shot them with bronze arrows or bronze crossbow bolts until you have 15 ranging and 5 defense.
Now go to port sarim jail and shot at the prisoners. Do this until you have 35 ranging and 10 defense (if you run out of arrows or bolts buy 500 new)
Now you can practice on the lesser demon that is caged in the wizard tower. It will be other players there mostly using magic. Do this until you have 60 ranging and 20 defense.
Continue at the demon or fight giants in egenvile dungeon. Now this will be the hard work. Do it until you have 80 ranging and 40 defense. Now you are a master ranger but if you want to get to 99 just continue at the demon.