Z-Dropping is a actually far from predictable being one of our few 1-frame moves, but you have to be very much in range to use it, which is totally fine since its 1 frame, and has a very persistent hitbox that can do up to 20% without a follow up.
The zigma upper as we call it here is still a decent approach. Predictable, maybe? Perhaps? Its pretty safe nonetheless, not unpunishable though.
On floaty characters we could combo characters up to 22%~ with just nair alone. Nair sweetspot could also work backwards for a true bair follow up.
There are also auto cancelled Dair follow ups on stage. Sometimes it may throw your opponent off because they don't really expect you to use dair on stage. Dair auto cancels upon two quick double jumps which can follow to an aerial or most importantly, Up Tilt.
Then there is DITCIT which is a must to learn to help kill with ease. (I don't need to explain this one)
Off-stage I highly recommend diagonal Metal Blade, Double Jump to Dair, Bair, or Nair. This tactic could definitely make it easier to guard, either to true combo or catch an air dodge and more likely get the kill since you made off stage an obstacle to return.
I'd also recommend near entirely replacing the charge shot with the leaf shield since its actually much safer to use. Also double jump when activating the leaf shield so when you land there isn't any lag. It has a lot more range than charge shot and because of its knock back, its mostly unsafe for an opponent to air dodge a potential string. (sometimes it true combos but only if you shoot it as a get up option.) There is also leaf stooling but that's not always reliable... but it does work!
Additionally with the leaf shield, you could also land on the ledge with it and take advantage of the invincibility of hanging on the ledge. It will be near impossible for you to get trumped (or hurt) as long as you're invincible. (the leaf shield interrupts them) You could use the roll get up to extend it making the leaf shield just like Charizard's flame thrower, meaning if they get up from the ledge too soon (50 frames), they are forced on stage rather than just hang there. Some characters have no other option because their recovery sucks or is too fast (in Samus case if she's gotta Up B) making this pretty useful you're really trying to pin an opponent down.
I hope that helped you TC.