The most common answer would be to visit the Tips & Tricks section as there are many threads were people share their experience with usefull things among them.
As for the basics of growing a youtube channel i always find it important that you have a organized Home screen, this means having a channel trailer, variety of sections like Populair and Recent uploads, Playlist section and if you livestream then the tab can be quite usefull.
Besides that have a eye catching banner and thumbnails wich grab the attention. have short and specific Titles, a well detailed description with possible links to social media and other playlists. Make the tags as specific as possible, is it entertaining, for pc, xbox, playstation? And use as much of this variety as possible.
Last and sure important the about section wich most don't do. Use this page to tell why you are unique and why should someone sub?