I usually bid a tad under the minimum recommended CPC. The most important thing is to have a good ad, with a good ctr. A lot has to do with the demographics you are targeting as well. For my demo(and most demos), if I get a CTR of .20+ then I am golden. I can get ungodly amounts of traffic and the ad will kick ass for weeks usually. But an ad with .10 to .16 will bring some decent traffic as well. After obtaining "quality" in FB's eyes, aka spending $1k+, I drop the bids slowly in about .05 increments until I am in a good profit zone. Then I just let them run. Again this really depends on the demographic, how much you are paying and what you are making on what you are promoting. This is from someone that spends 5k-10k a day on FB.