rubiks cube - How do I become a sub-30 cuber?

I am a sub-50 cuber right now. I am currently using the Fridrich method, I take about 2-5 secs to solve the cross and I am learning the 21 PLL algorithms. I am learning one or two PLL every day. I am using the 2 look OLL that uses 10 algorithms in two steps.

With all these have only a record of 32 secs and a average of 46 secs. Do you have any tips on becoming a sub 30 cuber or even sub 20 or sub 15?