1st and not least. is vote. you get a vote present which gives 1000k Gp ( How hard 1-10 ... 1 )
2nd is Thieving. This is good to do when you start off ( How hard 1-10 ... 2 )
3rd is Pking. This is an obvious money making way. but this ranges on who you face.( How hard 1-10 ... 5 )
4th is slaying. This is only for high combat levels mostly. its very hard to do without 43+ Prayer and 40 def is also recommended with either 75 str range or mage ( How hard 1-10 ... 8 )
5th is bossing. Very difficult for low or medium levels. High Combat is highly recommended and doing it by yourself isnt recommended so try and get a team. ( How hard 1-10 ... 10 )