Here are two short tips on working with blocks. 
First, to copy entities nested inside regular blocks, open the block in block editor, copy (CTRL+C) needed entities, close block editor without saving, and paste (CTRL+V) into your current drawing or any open drawing.
The second tip is to quickly edit an attribute in place without using the dialog box.  Just use the ATTEDIT command.
Notes from Cadalyst Tip Patrol:  There are a few ways to copy entities within blocks.  One is to explode the block, but that can cause a mess and you typically want to keep the block intact.  That’s why you have a block. The method in this tip is a better way.  It takes advantage of the clipboard in Windows.  Another way is to use the Express Tools command Nested Copy.  Just type on the command line NCOPY and it will copy a nested item (from a block or xref) into your current file.  It places the object on your current layer. Tested in AutoCAD 2009.