To get started you'll have to trade with Orowen (skilling store) at home, she's located at ::shops.
(STEP 1) Get 20 crafting by buying 6 pieces of leather, 6 needles and 6 times thread.
Use the needle on the leather and make 6 leather gloves. You'll end up with having 20 crafting.
(STEP 2) Trade Orowen (skilling store) and buy 35 uncut sapphires. Skilling in the Wilderness grants you an extra 25% experience bonus.
Go to ::mb and bank everything except the sapphires and chisel. Pull the lever (you'll enter the wilderness) and use the chisel on the uncut sapphires. When you're done with this you'll have 55 crafting.
(STEP 3) Go back to Orowen (skilling store) and start buying uncut dragonstones. You'll need a total of 1002 uncut dragonstones to end up with 99 crafting. (If you don't have the money for 1002 stones you'll have to buy less and repeat it after you sold the stones, continue reading the guide and everything will be explained.)
Buy uncut dragonstones at Orowen (skilling store) for 9.000 each and make a preset like shown in the image:
Don't forget to include two cheap items as gear or you won't be able to use "equip last preset" in your quest tab.
Do the same as you did with the uncut sapphires (step 2) and go back to ::shops. Now you'll have to sell the dragonstones to the Shop assistant, you'll be able to sell them for 10.000 each.
You will need 9.018.000 for 1002 dragonstones to reach level 99 crafting.
Remember that they can be sold for 10.000 at the Shop assistant so you'll end up having 10.020.000. Free 99 skill.
TIP: I didn't include the use of Bonus XP Scrolls. If you combine these scrolls with skilling in the Wilderness at ::mb it'll be much faster.