This article isn't going to tell you to make engaging content. I'm going to assume you are already doing that. This is going to tell you some basic tactics to get more clicks and hopefully more subscribers on your channel. Promotion without promoting if you will (I won’t go over advertising yourself because if you’re already on this forum site, you already know that much). YouTube is just a glorified search engine so if you make your content advertising, people will come to you.
Thumbnails – You want to be as eye-catching as possible. There are 3 main ways to do that in a thumbnail.
1. Bright and Contrasting Colours. Avoid using excessive white since that’s the colour of the YouTube webpage. If you are using white, contrast it with black. Yellow contrasts purple, blue to orange, green to red etc. Look at your logo to see if there’s any good colours to use there (it will assist with branding yourself). Getting good with Photoshop will help you learn how to make an image that stands out as much as possible.
2. Big Faces. Every thumbnail should have a focus point and psychologically, humans are attracted to eyes. Use this to your advantage and make sure you have a good mug shot of yourself or a character relevant to the video.
3. Boobs. Boobs work well (heck the highest trending media on this website is an uncensored HuniePop sex scenes video)
Those looking for a good elaboration should check here:
Titles – The general rule here is to be vague, but not too vague. A show like Game Theory uses its subject matter and capitalised trigger words to get your attention but doesn't generally tell you anything other than the subject matter in it's title alone, and that is all you need to do. Words like “Gameplay, commentary or play through” are completely pointless and distract people. Avoid them without exception.
Search Engine Optimisation – Did you notice a surge of Star Wars videos being published prior to Star Wars Episode 7 being released in cinemas? That was no coincidence. Doing a video of something relevant to the news helps it to trend. For example, if a new Pokémon game was coming out, you could play that new Pokémon game or a previous entry in the series to help yourself along. Of course bigger news means bigger trends. Even game companies like EA do this by releasing Star Wars Battlefront close to release of Episode 7.
Sub4Subs – DON’T EVER USE SUB4SUB GROUPS. They are a scam and will not result in higher publicity. The majority of people in this places won’t watch your content and it gives a bad image if you have 1000 subs with 5 views per video.
Do try to be unique – While I'm telling you rules to follow; you don’t want to look too similar to what is already out there. Differencing yourself from others gives a more individual style of branding and whether people realise it or not, they will pick up on it.
Hope you have found this article helpful. See where it takes and I wish you all luck to the future