Guides to Merching?

You take into account that if your risk is high you want to earn big money so you wait. But the longer you wait the more likely an item is to crash. Personally I look at 10% if an item goes up 10% I will resell if it goes up less after a day I will wait. There was a time I did a merch and in 2 days it went up 8% the first day so I bought more then it went up 22% the second day so I sold. That particular merch I only made 1.9m. But you just have to take a shot at what you want to make and what you value each item to be in the game. Like when dxp gets announced buy up all resources and then dump them a week before that another thing I like to do every dxp. Either way a lot of it is a hope and a prayer since you can't predict what the community will buy but with jagex showing trends it's a lot easier to predict