You might be wondering what timing has to do with location. But in a four-dimensional space-time reality, timing has everything to do with location. It's science. Albert Einstein would agree, and if there was one dude who could hail a cab like nobody's business, it was Albert Effing Einstein. Know your rush hours.
Also be aware of what day of the week it is. Taxis go where the fares are. If it's Tuesday at 5pm and everyone is leaving work, Midtown and the Financial District will be swimming in yellow.
If you're not there, be on the avenues coming out of there and hope for the best. If it's Saturday at 8pm, the same applies for the Village. And Uptown. And Downtown. And the West and East sides.
You didn't really think it was gonna be that easy, did you?