You need text mining technique to find what your viewer are talking about in the comment section, more positive view and higher number of like/dislike will help you to rank higher in YouTube search. Your channel also need to make at least one high quality video to attract enough View, then the rest is more easy to handle. As for key word, you need to change your common key word in your description and replace them with less common ones, that strategy can really help you standout on other youtubers. Longer description definitely helps, you also need to avoid vague word, the more accurate, the better! I can write that for you. Another thing you need to know is your viewer behaviors, what time of the day did they watched? Did they drop out your video and change to other videos even when your video didn't finish. That all depend on the most important part--the quality of your videos. you also need to upload frequently, that is also very important. You can make more people watch it if you make your video more formal and run it like a true business, which means you need to choose your channel name carefully. Also remember to greet your audience in the start of your video, it is a good practice if you want people who watch your videos consider to subscribe you.