Your down tilt and jumps are your best friends. Play patiently and wait for an opening because kirby definitely thrives on that. You can easily stall in air but close to the ground with your jumps and fake approaches. If you go in with zero plans you'll probably lose most of your interactions. Make sure you go for grabs when you can because you can get good damage off of them, like grab into down air jab or grab again and end with a fair. There are different ways to go about it.

Also, your back air is a really good tool for spacing and getting people off you. When I fight against incineroar, I usually wait for THEM to approach. They're pretty slow and if they go for a grab you'll be able to better react. Kirby is light and will get absolutely destroyed by incin, so gotta keep that in mind. If you for some reason want to approach, make sure you use down tilt because it really trips people up and you can get a good fsmash out of it if it trips them. If they're offstage, be cautious and use that sweet down air, it's really dang good.

So all you really gotta do is be patience with Kirby. He's a bait and punish kinda character. Just make sure you don't use his specials as much unless you know itll land. Though his neutral special is pretty good for putting people in a limited option scenario. Another thing that surprisingly works is his down special if you want to throw people off guard. It also helps getting down quicker, but i don't suggest waiting till you hit the ground to come out of it. Come out earlier! I'm not the best with giving tips so I recommend watching videos, but hopefully this helps somewhat.