You're likely to reuse a really terrific pattern many times, which will more than compensate for a few others abandoned during the process of elimination. Of course, all my checkpoints apply equally to patterns that you already own, and may help explain why you've been less than delighted with some of them. Perhaps this will inspire you to edit your collection down to winners only. A good pattern recognizes the complex, nongeometric shapes that make up the human body, and is drafted to allow flat fabric to wrap round bodies gracefully. Look for pants patterns with noticeably shorter front crotch curves than back curves.
Real shoulders slope, from the crook of the neck to the end of the shoulder.
Necks bend forward far more than they bend back. Collars won't sit up straight without a stand. The small of the back curves. A relaxed arm isn't straight, it bends significantly at the elbow as it hangs at your side. You can't shape a sleeve with only one seam.