Bargain taxi?

So I halfway through walking I thought 'let's take the subway!' but once I got down there I didn't know where to go, and I asked people in Chinese 'where is this' but they didn't know exactly where (I took a picture of the mall, so it was vague). So I left the subway, walked a long time, got fed up and went to a taxi. Now here's the difference, when I was with Steven he always hailed a taxi, he never went to a parked one. There was my mistake because I went to a parked one. He said '50. 50 to go there' and I was like 'uuuuuhhhhh' and you know me, so I agreed. Yesterday it cost us 15 to go! So I got ripped off.

Inside the mall I got better at haggling (giving a really low price, then going up, or leaving until they made a better offer). When I left I was looking for a taxi and this guy calls to me and shows me his taxi (which is registered don't worry). I showed him my hotel address and he said '30' I said 'no 20' he said '25' and I said '20 or no'. So he said ok. I didn't know you could haggle with taxis! That would have been good to know xD