The rather strict rules of voice-leading as we might first be taught aren't meant to summarize the art. They are to be taken as a spring-board into a greater but harder to define understanding of music. It looks like you've had enough of those beginning exercises in simple 4-part homophonic part-writing.
Those patterns and "rules" of voice leading that we might be taught are supposed to be easier to apply and understand than the broader principles of actual practice. Composers don't always resolve tendency tones and might use more skips than your instructor would have preferred in an intro to voice leading class. But tendency tones are called tendency tones for a reason, and skips reduce our ability to hear the integrity of a voice, so they are solid concepts to understand, for example.
Most generally, voice-leading is just the way voices move about in a piece. Usually, good voice leading means that each voice feels smooth, atleast somewhat independent, at least somewhat interesting, and supportive of the background harmony and feel of the piece. Besides the standard ways we're first taught to voice-lead, it helps for voices to possess their own melodic or rhythmic aspects. You can look to contrapuntal devices. But I'm not aware of any hard-and-fast criteria.
I wouldn't be too stuck on removing "non-harmonic tones", as they are part of the actual progression of the voices (voice leading).
Let's use a phrase from Haydn's Piano Sonata in Eb (Hob XVI:49) to demonstrate some simple examples of nice voice leading (see Brendel's performance, segment ~0:35-0:47).
The blue lines connect notes in an independent voice. The green dot shows the entrance of an independent voice, while the red dot shows its exit. The orange dot shows the entrance of a voice as an entity that is largely subordinate to the top voice, and the orange lines emphasize this subordination.
Notice that on the third beat of the first seven measures the upper voice drops a step and then makes a substantial leap. This adds a feeling of unity to the voice in the phrase and adds melodic interest: nice voice leading. The step down resolves the suspension over the change in harmony on each third beat, and the jump up emphasizes the first beat of the next measure: nice voice leading. The middle voice enters on measure four to fill out the harmony to raise intensity, but also provides a bit of counter to the first voice: nice voice leading. It drops out at the end of measure five, temporarily reducing the intensity and shaping the phrases' mood. But it comes back in measure eight, and this time in a more supportive role to the first voice, really raising the intensity. In measure 9, the bass now has to get in on the escalation, doubling at the octave and rising up to meet the upper voices in a cadence. The upper voice harks back to its suspending-resolving ways of measures 1-7 by making the cadence metrically unaccented. Nice voice leading.
I'm not sure what subjective feelings of these (or any) were intended by Haydn, but the phrase sounds pretty cool to me, and it's largely due to the way he progresses the voices.