The obvious answer is more practice. Most players tend to avoid side pocket shots unless the object ball is directly out from the pocket. Anything with an angle makes them try a cross bank or an extreme cut to the corner. Other players will use extreme efforts (spin & speed) to avoid a cue ball position that forces an object ball shot to the side pockets.
What many people overlook is that the side pocket is the biggest pocket on the table. The angles to the side pocket where an object ball can be made is over 3/4 of the table surface. The only areas where you cannot make an object ball are shown with the diagram below. Any object ball inside the line cannot be made in the side pocket; any ball outside the line can be made.
The closer to these lines, the smaller the pocket size. This is no different than running a ball down the rail for the length of the table. Both shots are targeting a very small pocket.
Your aiming point for any angled side pocket shot is just inside the far tip. When shooting into the tighter angles, use slow speeds. The more open the pocket, the higher speeds can be used. But because of the line, slower speeds are recommended.
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