Hello Merfect,
you have been helped already, allow me to throw in my hat still.
First I recommend, if you have not already done so, to experiment with your character of choice in the training mode to see what works and what does not, to get familiar with the range of attacks, their exact effects, their starting time and cool-down and whatnot. In Smash Ultimate we even got the nice tool to see how far any given opponent will fly when hit with a specific attack. I find that quite useful.
Even if you find silly stuff that you think will never work in a real match, practice it still and you will find yourself equipped very well for pretty much every situation, how uncommon it may be.
You could try and practice things until you can do them 10 times in a row without fault, if you like. That may help to let certain techniques sink in.
There you can try things like DTilt > Dash-Grab > D-Throw > U-Tilt > NAir > Farores Wind for something around 46 % (do not expect to land something like that in a real match, but you may try of course and who knows what might happen... some people still try to hit Ganondorf with simple melee attacks while he is charging his Warlock Punch and many people blindly run into someones fully charged smash attacks...).
Please take into consideration however, that I'm not a pro at any smash game and that results may of course vary from person to person. Still, I think it is never wrong to practice
As for the gameplay itself, I can only speak for myself, but I find it very helpful to approach enemies with NAir, Dash-Attacks or even grabs. Of course the exact strategy has to be adapted from opponent to opponent, I always try to use the whole moveset of a character.
The Phantom I only use for edgeguards and mix-ups. Sometimes it may prove useful to be used more commonly in neutral, but I personally dislike attacks that take long and are easily avoided. The Phantom does take quite some time (unless you send it to charge with a fist) and is easily avoided as well (unless your opponent is somehow disabled or off-stage).
As edgeguard I find the Phantom very useful.
Also your Up-B (Farores Wind) might be used in the neutral game and surprise your opponent and maybe even hit a KO.
Please also do not forget your F-Tilt. It is rather powerful
With lots of practice you will find your personal playstyle and be more succesful.
I run into lots of Zelda players online (I personally perceive Zelda as the second most played character right now, the most played being Mario [at least in my experience]) and many just spam blindly the same moves over and over and over again without improving results (most of the time they spam the Phantom and smash attacks). Please do not be that kind of player. Zelda is rather versatile, try and use everything she has in store
Best regards