A lot of people have a problem where they say “my shot was straight-in and that’s why I missed it”. This terminology is incorrect. The problem is that when a ball is perfectly straight in, there’s no defined spot to aim at and you’re stuck aiming at the whole ball. This makes it hard to find just the right spot to aim for.
Most people will just line up their shot, they’ll look at the center of the object ball and try to hit that. They may be successful half the time, but that means they’re unsuccessful the other half of the time. Using the technique below, you should be able to adjust those odds heavily in your favor.
First, adjust how you look at the ball. When you look at the object ball, try to match up the left and right sides with the cue and object ball. Imagine that there are imaginary rails on the left and right sides of the cue ball and they extend toward the object ball. When you get down to aim, make sure you can see those two lines in your head. Take your shot and listen for the sound of your ball going in the pocket.