1) Thumbnails, titles, tags: make sure that your video is optimised for success. The 'three T's' all need to tell a cohesive and compelling story.
Thumbnail tips: make sure it's a good size on all devices (check on your mobile), close ups of faces work well, high contrast and bright, make sure it accurately represents your content.
Titles: Include relevant and descriptive keywords towards the beginning of your title. Keep them concise. Always represent your content accurately. Update them so they remain relevant over time. Make sure that together with your thumbnail, they create a cohesive story.
Tags (& descriptions): Create unique tags that distill the most important video topics, characters, talent names. Include a mix of video-specific and more general (but still relevant) tags. Use quotation marks (“) to convey multi-word tags (ex: “Harry Potter”). Like the title, a video’s description field is valuable real estate that helps audiences and YouTube’s discovery systems understand what your content is about. Only the first few sentences of your video description will appear in search results and above the fold on a watch page - so make them count! Accurately describe your video in one to three concise sentences at the top.
2)PROMOTE, promote, promote. A lot of Youtubers try to create a viral video. This is essentially like hoping for a number one hit, the odds are unlikely. A lot of the successful videos on YouTube have media spend behind them. And you don't need to break the bank. Try YouTube's TrueView. It's cost-effective because you only pay if someone watches your video for 30 seconds or more (ie. they are truly engaged). Views cost around 7pence (GBP) (depending on auction intensity, your industry, etc etc).
3. Create content that is regular, consistent and appealing. Be the best answer to a question. What are the common questions that people ask in your area? How can you add value. Create a set up that is easily reproducible and create content that is helpful. Check out O2 Gurus and Sorted Food YouTube channels. YouTube's algorithm looks at ENGAGEMENT = the length of time people have watched your video and the number of subsequent videos on your channel they have gone on to watch. So you want people to keep engaged and to follow on by watching another video of yours.
4. Have a good YouTube channel that you regularly update. Create autoplay playlists to push people to watch more of your content. Add annotations into your videos to drive people to another video on your channel. Get people to subscribe - subscribers are gold dust. They are twice as more likely to watch a video than non-subscribers. YouTube realises this and makes everything geared towards subscribers e.g. on everyone's YouTube homepage, there is a left hand column with a list of all the channels you've subscribed to. And a notification against each of them to show how many new activities each channel has. Activity doesn't just mean a new video, but can also be a comment you've made on your video, a new playlist you've created (you don't need to own videos in your playlists). So keep active.