Not-So-Negative Space?

How can I make icons like these?

and
credit x, x

I've tried looking up multiple negative space tutorials but I still seem to have problems. The edges aren't jagged but they aren't super soft either and the textures seem to mesh perfectly.

Mine turn out like this:

and this (Note the jagged lines in the second picture).

I use Photoshop CS3. Any help would be greatly appreciated!