Dave, words are cheap. You say you want to go faster? Fine, just go faster ... .
Are you locking up in the braking zone (or ABS pulsing)? Are you spinning out in the corners? If you are on the throttle or the brakes, are you on 100% ALL the time? No? You are not trying hard enough. If you are not doing those sort of things, you are not pushing the limits. Going fast is about finding the limits, usually by going over them, and then consistently driving at, or just below, those limits.
But you need to want to do it - you need to NEED to do it. You need the competitive drive to make you push those limits, to take those risks. You need to be able to handle a written off car, or a damaged one, if that is what it takes. To illustrate this (and I am no ace), on my first lap on a circuit, and with the instructor sitting beside me after a couple of laps in the driver's seat, I spun the car on the third corner. I was pushing. I was also being a bit stupid/overconfident too, but I was prepared to push myself, the car, and to take risks. (You Mexicans have a problem there, because your circuits can bite pretty hard - we have Wakefield, which is great because it has a lot of run-off space, and pushing/finding limits is relatively risk-free.)
You don't
need all the things mentioned up thread. You can do it, all by yourself. The Tander vid is an excellent tutorial on lines generally and PI in particular, and data can help, driver training (with a good trainer) will speed up the process. Seat time is essential to get to know the car and its characteristics. But none of that can change your mindset.
You may not be that competitive animal. You may not have the last 5% of the necessary skills. You may not want to risk a DD because you NEED that car tomorrow. That is cool, what is important is to know yourself, know your constraints, know what you want, and then drive accordingly. If that means you are not getting 100% out of the car, your lap times are not where you would like, so be it.
But most important thing is to have fun, and be smiling when the day is done. Everything else is secondary.