I think there are a number of elements coming together to being an accurate player. Obviously being able to execute a passage and having built that ability is the first hurdle. Diligent and methodical practice is the place to start to get the passage under your fingers and build the strength in the chops to be able to play the part. But how do we play consistently every time we have to play? I feel that it's most important to have the notes, pitches, entire phrase, in your minds "ear". What does that mean? Play the part first so that you accurately hear how the part sounds with correct pitches. Then sing it back with the same phrasing, pitches, articulations etc…. until you really hear it. The next time you practice the phrase start first by singing it to check how accurate your minds ear is. Are you really hearing the pitches correctly? Once you're able to really hear the notes before you play them, you're well on your way to playing much more consistently. Now, play the entire phrase, not just the starting pitch, the whole phrase from beginning to end in your minds ear and hear how beautifully played it sounds. You've just heard your successful execution of that phrase in a musically flawless way. Now with that still ringing in your ears, simply play what you've already played in your minds ear. It's amazing how this technique really works. Try it next time there's a difficult part that's giving you some trouble. Or if there's a particularly high note you have to come in on, practice hearing the note with a perfect attack right down the center, and then simply repeat what you've already played.