Cyclone is going to be your easiest form of tech chasing, and probably best way against mid % fast fallers. A couple things to keep in mind, however. First, both of cyclone's hits can be crouch canceled at low percents and since cyclone has a fair amount of end lag, you are easy to punish. If they CC the first hit, use the rest of cyclone to get as far away as possible unless you're fine trading the second hit for their punish. Second, once you start going in a direction, you can't turn around easily. So ideally you want to start cyclone right on top of where they hit the ground and then react to their tech option.
Like I said, cyclone is great against fast fallers at mid percents. It can start up some nice combos. But a better combo starter will be down smash. This will be better at lower percents than cyclone. Work on placing yourself in a position where you can cover 3 of the 4 options with down smash. You are probably less likely to be as successful with this option than with cyclone, but it will set up much more often for combos.
You can get some good things off of these, but you are going to need to read your opponents techs plenty of times. This is where you will get the most out of your tech chases and punishes and lets you be more creative.
With platform tech chasing, what I like to do is a rising nair if I think they will miss their tech/tech in place. If they are high enough percent, your weak nair hit will pop them up just high enough to get an easy follow up hit. If I think they will tech to the sides, I like to wave land on the platform and then either tech chase to regrab/downsmash/up b, depending on their percentage.