First what you will want is a basic set of tools and a desire to get some metal and deeper world objects. After you get that, you want to start off your mine by getting a area that wont hit anything you don't want it to thats underground at that time, you can also start the mine off with a door at a lower level. Then you dig a 3x3 area down a little ways, mabye 10 blocks, then you will want to dig a 3 tall area in the wall 6 blocks under the platform. The charecter will fit in the 3 tall area without falling out but can still jump up easily.





After that you want to keep digging and make a 3 tall depression in the wall with 6 blocks inbetween each. You should be able to jump up the wall if you then run against the wall and jump.










This will work for going to the oposite wall as well as the area above you. I make my mines have two sides climable just for the ocation I want to get off and into a cave or other area, where you just make the 3 tall depression into a 4 tall one so you can then go through it and just jump to the other side of the shaft.

If the area inbetween the depression is 7 or higher, you wont be able to jump to it, and if its less than 6 you can jump and get on it, but it dosn't maximize the blocks per jump ratio. Also, be careful not to fall to far, you WILL die if you fall to far and don't have enough water at the bottom.