You can see my first fully recorded attempt on the Vizzed Gameplay Channel: https://www.youtube.com/watch?v=DQ-RmLTM3sk

Any thoughts or comments on this run, other than the obvious mistakes I have to avoid? Any bit helps!

I'm a little past the 4 minute mark, and you've already made a number of what seem to be mistakes.  Don't get me wrong: You're good.  But you probably will have to put in a good amount more work in order to prepare.  Have you thought about detailing your route on paper before putting it into practice?  Have you taken inspiration from other runs and learned from their mistakes?  Anyhoo, keep up the good work! 

If you're talking specifically about the route I took there, that's the easiest way to get to Candy Constellation. I use the checkpoint mirror later in place of using a more out-of-the-way route. There aren't too many ways to get there.

If you're talking about execution, I know I have a LOT of work to put in, still. My run is still only two or so months old, and college work has kept me from putting in maximum effort in this. Priorities, man.

Moreover, while Mednafen's emulation is pretty stellar, I won't deny that I probably made some mistakes due to differences between emulation and true Virtual Console, as well as the gamepad in use. I know it's no excuse, but it can explain the plethora of execution failures.

I'm going to record another run now. It'll probably also be on the Vizzed channel.

EDIT: Whoops, I missed answering one of your questions. Yes, I actually have taken inspiration already from other runs. A TAS of the game showed me the method to be able to bypass the intro stage gate without having to wait for the other Kirbies (ultimately a 5 or so second time saver, depending on when the others arrive to the room). A pro speedrunner also helped me with the starting route going to Area 9, and taking a slight time waste to grab stone ability in order to demolish King Golem and save more time than I lose (Missile can traverse the stage faster). Same applies for when I get UFO to deal with Crazy and Master Hands later on in the run; it was by help of the same speedrunner, although I didn't know at the time how well it was going to work. Another speedrun I watched (whose time I have since surpassed) showed me to use Burning for the area before I can get Missile, although I still need to be better overall at using it.

On another note, the second full run is complete and recorded. It's being processed into mp4 format now, and I'll upload it for Vizzed as soon as I can. I shaved more than three minutes from my time in this run by simply executing better. I also reconsidered the order of bosses to face so I can feel better as I move along in any of my speedrun attempts.

EDIT 2: The new attempt is up! https://www.youtube.com/watch?v=YqDkZkf2Irs