Note: To add chest dig a 2 wide hole next to bed and put chest there.
Step 1: The Proper Place
Find a place that's suitable
. Flat not that important you can make it flat.
. low the lower it is the less you have to dig to get to bed rock and diamond.
. (optional) near water if you want to use boats as transport
Step 2: The Lower Level
The lower level.
dig a hole 9x5 and 4 deep
place a layer at the bottom for the floor
put cobble on all of the walls and make a stair case
build a ceiling
When done it should look like pic 2.
Step 3: The Defence
Go in side and remove the upper level of cobble so that you can see the bottom of the trench.
What this dose is any mobs that would be right by your door falls in and you can punch its legs but it cant hit you.
Step 4: Build Walls
Step 5: Dont Let the Door Hit You on the Way Out
build a ladder up your middle post
Build a 3 tall pillar on the other side of the trench then connect them with a piece of cobble
You can add a little 3 high "u" around the hole in the roof then put a door there.
Step 6: The Roof
build a roof on it
Step 7: The Fire Place
Step 8: Furnas Bed Work Bench
Step 9: The Shaft
The mine shaft is just dug out of the wall I'll let you decide what you want to do.