Jesus christ - I wouldn't follow half this advice - I've owned many obby maulers in the past and i'll tell you what I think is best;  
  
80 str Is when it gets fun, everbody is a low level gmauler and can't hit through your 72 HP 
train to 50 range then ONLY train while pk'n (range - obby is stronger + better than only melee) 
55 slayer is OK for when your acc is finally maxed out with range and you cba to get any more str levels 
Get Mith gloves 
Get 15 prayer for avas ( DONT TRAIN IT JUST QUEST) 
  
hf buddy hope i  helped