Dont touch defence and pray would be a nice start, trust me when I made my first pure I didnt know that I should lay off the prayer but I trained it either way. What I would do if I were you is train attack to 40 and strength and range to as high as you can. That would be a great start, then you can chose to train defence if you like to becoming a rune pure. But remember the essentials, your strengths will be your strength and range and train those to as high as you can take them. You may also want to train mage to get the extra mage levels I found that fairly useful. But most importantly I would suggest you start picking up the bones you get and start banking them, they will yield a fair bit of your income for now. Then I would suggest air running as a good way of making quick money and you wont need to watse time on training your skills.