To improve minecraft I'll add some new blocks: Marble block, granite block, cement block, limestone block.

How to make the different blocks: The marble block, granite and limestone block can you find it in the nature, you use an pickaxe on it to get a block of it, and you'll have the option to chisel it.
But the cement block should be made by mixing sand, gravel, clay and limestone together and putting in a furnace, the cement block should also be paintable(you use dyes on it).
From the different blocks you should be able to make stairs and slabs.