A few 'professional' tips on how to use Link from a man who's reaction time is as low as ~3 frames:
N-Air (Back, Dirty) > F-Smash (after roll) at high percentages will garner either a KO or a decent range as your opponents will be on the ground in Jab Lock and bounce, giving you enough time to react with both hits. If they are too far, JL will not work and you'll likely either send them far with the first hit or miss entirely and they will recover. Use with caution.
His U-Tilt can be just as annoying as Mario's U-Tilt and Sheik's F-Tilt, but also more damaging as it covers more range and has more damage, as well as low knockback growth on low percents. This effectively makes his chain combo useful on the larger characters due to its very wide range in which he does it. It can even lead into a U-Smash or an FF U-Air.
D-Tilt is an instant U-Air hit and is effective at poking shields and dodging with its low frame amount. It also works well with N-air and U-Spec by comboing into either attack.
Talking about U-Spec, there is a chance that using it in the air will actually KO your opponents at a lower percentage on the last hit; I've tested and done it around the 78% range, as the indicator of the KO, the KO Shock, was present and my opponent was sent to the upper blast line quickly. The U-Spec is definitely one of those moves to bait your opponents in the air, and it's surprising on how it will kill on low damages. If on the middle of the stage in the middle of the air, it will KO at around 120%, which may not seem much, but depending on which opponent, it could be lower or higher.
And lastly, make sure to always use the tether button as fast as you can if you grab the edge of the stage with Link's tether, as it will out-prioritize other grabs and make meteors miss most of the time. But the timing is definitely important if you want to make the meteor miss.
With that out of the way, my next post will be quite character specific.