Okay once you make an account,you start out lvl3,well the best way to train for free members is this way
Lvl3-lvl12 train on chickens in lumbridge(So you can train your prayer too by collecting there bones and it will be even with your level)
lvl12-20train on cows in lumbridge or falador(same thing with chickens,they are a bit stronger though,and justa tip,cow hides are sold for 100 each,so good way to make money as a noob )
lvl20-35 al kharid guards(easy to kill,and you gain lvls fast!)
lvl35-60 Hill giants(they drop big bones,lots of prayer experiance and drop lots of other valuable items too!)
lvl60-80 Moss giants(Same concept as hills,but more valuable items and stronger)
lvl81-126demons(strongest there is for free players I guess)