1. Focus on content which isn't well served by other channels. So if you're making videos in a very crowded category, it difficult to outperform the competition. For example if you start making video about phone reviews, your video might not get discovered unless your video is more interesting other's, because you'll already find many people producing amazing phone review videos.
2. Sharing your videos with friends on social media and relevant forums.
3. Titles and thumbnails followed by your descriptions are more important than tags.
4. Make your audience happy and produce those kind of constants that they like. Uploading 2-3 videos a week won't help you if your audience don't like it. Ask for feedback from your audience and step ahead accordingly.
5. Is it true that YouTube algorithm doesn't promote short videos? No it is not true, there are many many videos less than 10 minutes even less than 3 minutes got millions of views. It all depends on how interesting your videos are. If your video is short but people like, share and watch most of it, it will be recommended.
6. Likes are one of the many signals that YouTube algorithm will promote your videos.