I could personally offer you a whole bunch of advice if you'd like, as a fellow Ness main! There's plenty of resources for you to grow here so you've chosen a sweet community. Funny enough, I'm actually working on a Competitive Guide now that you mention wanting to improve. Soon going to make a beginners guide into Smash 4 also if you're interested.
Best thing you can do for yourself is:
Find the
right people to practice the
right things with. And then condition yourself to play in the
right environments.
Here's one of the "right people" for a Ness main like yourself. His name is Nakat, he's the 3rd ranked Sm4sh competitive player right now on smashboards. His Ness is godly and he made a guide about it!
Ness Guide by LoF Nakat
some "right things" are character mastery and mechanics that would land you first, such as learning
core fundementals or
specific mechanics!
Smash Theory: Zoning and
Smash theory: The Neutral good core fundementals!
Perfect Pivoting and 5 Tips n' Tricks For the Smash Newcomer are two nice guide on mechanics to add to your gameplay!
The "right environments" are places where you can reach people who consistently win tourneys or place highly in tourneys. Heck, even people who have a competitive mindset would be really stellar, but primarily you want to play with people who dominate you. If you want to become a god, befriend the gods.
I'll link you to the guide when I finish editing it so you can tell me what you think!
Take care, yung Akuma!
P.S. here's the post I made earlier, soon to be a topic titled "How To Reach Competitive-Level Play Quickly". Still working on condensing it and making it into a topic. I wouldnt worry about it too much right now, and would instead focus on the second post about resources that are invaluable as a competitive player!