counter-clockwise: advance
clockwise: retard

Use a timing light, don't just guestimate or run it at full-advance. Generally you don't want to advance or retard more than 2 degrees from stock, which is marked on the crank pully. The white mark by itself is TDC, the mark in the middle of the cluster of 3 is your stock timing, and the marks on either side of it are 2 degrees advance/retard.

*these markings are for a B18C*

If you don't know the proper way to set ignition timing, go here:
http://www.c-speedracing.com/howto/timing/timing.html