Taxis in Manila do one of two things: If you're standing there waiting for a taxi to appear, they hide. Sometimes they'll drive by with the light on, but they won't stop, because that just means they forgot to switch the light off. You can wave your arms around, shout, whistle, whatever you like, but you'll be waiting quite some time.
However, if you have no need of a taxi and are just walking down the street, they stalk you. They drive past and honk, slow down and crawl past you, and (especially irritating this one) if you try to cross the road, they'll actually stop in front of you and block you from crossing, under the misapprehension that you want to get into their cab.
So, if you're waiting for a cab, start walking and one will find you soon enough.
I'm not even going to bother mentioning the bargaining and fights over whether or not they're going to use the meter. Oh no. Suffice it to say if a taxi driver uses the meter without arguing, I give them a tip. If they haggle, bargain, whine or try to cheat me in any way, they get no tip at all. Except if they do that "pretending not to have change" routine. Grrrr.