Help me! Learning to corner!

I've been driving my dads 93 nissan 300zx. The only upgrades that would help performance right now are Brembo brakes, Yokohama tires, and some racing shocks/springs that start with a "k" (Forgot the name but it sounded chinese).

When I am turning the car (whatever speed or angle), I can feel a point where the car seems like it doesn't want me to turn the wheel anymore, at this point, the tires don't squeal or chirp. Is it normal to feel that? I have gone into the grass 3 times because the car didn't turn sharp enough, with only like 20 minutes of hard driving experience. It is not asphault. Would it benefit to turn the wheel past this point I'm feeling? And would the car handle it well? And how do I know when to stop turning the wheel? (while not using the gas around a corner). I got the basics of powersliding down, but I'd rather learn to drive properly. Thanks. Also, if it makes a difference, there is probably an added 65lbs in the trunk from sub and amps.

1.With the car parked turn your wheel all the way left counting number of turns to lock(point at which you cannot steer anymore).
2.Turn wheel all the way to the right repeating step one. now add A and B and C equals your number of turns lock to lock.while cornering this is your limit. If you cannot get to lock while turning check that nothing is broken or obstructing your steering. If you turn too sharp you will understeer(front wheels not getting traction to turn properly) if this happens go into the turn slower. Otherwise practice on different cornersin a safe area. And remember you should stop braking and begin gassing at apex.



Or you could go to driving school.