I'm not too sure if I can give you the best answer but I can tell you what does get people more subscribers:
- Be creative: Being creative is a huge key and by doing so you probably will be original.
- Be original: Original content is desired as doing something someone else does will usually not fare too well. My best series aren't let's plays like playing Minecraft minigames but stuff like JWong Edits, the Cube, and Montage Parodies (although a lot of this has been done too).
- Seek opportunities: This is something hard to explain but basically if there's something that can help your channel do it! Opportunities lead to more opportunities.
- Consistency: I have been terrible on this part and I can say that this is why my subscriber and view count has slowed but if I was consistent it would grow a lot better. So yes uploading on a schedule that's consistent helps.
- Have a great personality: One of the most important parts in YouTube. Just be friendly and positive and that vibe attracts people. People will watch you if you can bring that to the table.
Hope this helps!