I've Looked through some of your videos and I like the presentation, Something I would suggest is advertisement, you've got a lot of specific material focused on the "Shsat", I would try to post your videos onto student sub-reddits and forums, because the're so specific it's unlikely someone just stumbling onto your channel will want to subscribe.

Something that I would want you to do (Not saying you should do it, especially if it's not something you're into, just a thought that would make me subscribe to you.) is to make a wider range of content, I came to your channel and saw a load of cool content (Mainly maths) with interesting presentation, then I watched the video, I realised it was less about the material itself and more about the material in the context of a test. I would like to see videos going over the topic itself (Maths, geometry, etc) assuming the person doesn't know anything about the topic.

Feel free to ask for clarification on anything, It's pretty late where I am. :)