Directories have been good sources of one-way links for a long time. It is a one of the easiest link building method especially for newer sites. But quality is still the name of the game. Some pointers in selecting the directories to submit to:

High PR - indication that Google sees some value in the directory.
Well maintained - listed sites are in the proper category
High Traffic - getting traffic could be minimal from directories, but majority are targeted
Kewords ranking high in SERP - Well optimized, shows that the directory is well-marketed and SEO'ed.

Which to avoid:
Link farms that pose as directories
Directories that require reciprocal links
Crappy ones with crappy sites listed

What are your thoughts? Care to add more pointers?

Good points .Thank you very much !