Hi Hi!
I have only just started out, so I will not claim to know much about this YT malarky but I can give you my perspective as a viewer!
1. I love your channel art, I think it is well thought out and clever and it gets across the nature of your channel very quickly and effectively, not to mention is is very cool looking frankly!
2. I watched your 'Big beautiful crystal growing' and your how to guide. First off, I think the crystals you are making are awesome, but there are a few things you should watch out for.
Big Beautiful
I would hard cut away when you are moving the camera, the shakiness causes a bit of motion sickness! easy to fix, similarly you may find it easier to position your camera at an angle to what you are doing, that way it won't get in your way so much. This would have been useful for the second half of the video where the crystal is being obscured by your t-shirt and we don't get to see it, video length is good and keeps your attention long enough, another silly little thing, there are parts of the video that could be cut out, I only mention this because, I personally would have kept the length of the video to the length of the song just so that there is a natural end to the song and the video at the same time!
In summary, the video has really good content, and I really enjoyed the music accompanying the video, there are just a few things you can do to polish up the video
How To
The first thing I would say is that you probably should have muted the background noise!
I would have preferred a voice over, even if this was done in post production. However if this isn't possible, then you might need to cut down the amount of text on screen at any one time, try staggering the text and maybe try a different font type, maybe with an outline if possible. I know that you fixed this in Big beautiful, so it shouldn't be an issue going forward, but recording freehand makes the recording a bit shaky also there were parts that seemed to lag in the playback, I don't know if this because of the original recording or a glitch that occurs when the video is rendered.
3. Thumbnails are informative and they get across the message of the video, but maybe you should try being a bit more clickbaity, also the text on your thumbnails blends in a bit too much, I would go with a bigger and bolder font that doesn't clash with the background so much! I've attached a mockup of one for you that I did in Pixlr
4. Your SEO seems to be pretty good actually, you rank pretty high in youtubes searches, I would compound this by polishing up your content and, unfortunately, being a bit more clickbaity! I would make a point of giving your channel a description and you will need to upload a bit more regularly. Other than that, your content is great and as I'm sure you can see from your viewership, your views far outstrip your subs so you just need to convert those viewers to subs and grow from there, then it will be easier to grow!
Best of luck and I hope this helped!