When using English you will often have to compensate for the spin of the ball by aiming at a different collision point on the object ball. For example, if you are using left English with the intention of pocketing a ball into the corner pocket to the right of the object ball, you cannot aim directly for the pocket, but should pick a collision point on the object ball that would normally send it just slightly to the left of the pocket to compensate for the throw.
What's actually happening is that your cue ball will not contact the object ball at the collision point you pick. You're just aiming there; it will do its swerve and curve thing and wind up at the perfect collision point that you would have aimed for had you not used English. Yes, there may be a small differential due to throw, but remember, that's usually not as much a consideration as properly adjusting your aim for squirt and curve.
But wait … if squirt sends the cue ball out in one direction and curve brings it back in the other direction, why would you have to change your aiming point at all? It seems like the ball should wind up right back where you aimed it. The answer lies in cue ball speed. The cue ball's ability to curve is dependent on when it begins to interact with the cloth and gather topspin.
A sliding cue ball will just keep sliding in the direction you send it. But a cue ball that is rolling end over end will interact with the sidespin that you applied and begin to curve. So if you apply right English, the cue ball will only start to curve to the right when it begins to roll end over end. That's when the right English will start to interact with the cloth and, voilà! You have a curving cue ball on your hands. If you strike the cue ball softly with English, it will stop sliding sooner, and it will begin to curve sooner. If you strike it hard with English, it will slide longer and start to curve later, and in cases of a very hard strike, it may not even curve back at all by the time it reaches the object ball. So you can see how you would have to adjust your aim according to how hard you are striking the cue ball.
Seems tricky doesn't it? Well, it's not much trickier than learning the difference between your contact and aiming points, which you should be a pro at by now. You just have to adjust your concept of the aiming point when using English. Again … it's all in the practice.
Now that you've learned the ins and outs of English, you should spend some time practicing it. It will certainly take awhile to get used to aiming at a place that isn't where you know the cue ball will wind up. It kind of feels like trying to hit the bull's-eye of a dartboard while aiming for the top or bottom of the board. It definitely feels strange and it's something you'll have to get used to. Believe it or not, it's not as impossible as it sounds, and it won't take very long. Just keep at it.
Practice your shots where you are trying to scoot the cue ball around the edge of an obstructing object ball. Also, practice using English to change the path of the cue ball off of a rail. If you strike the cue ball on the right, after it collides with the object ball, it will travel to the right off of the rail.
Keep at it and don't give up. The pros had to go through it, too. Remember, they were once where you are now.