1) Make sure your content is great quality, particulary the first few seconds.
(I checked your videos. The videos are great, lots of good information, but you are using text to speech software I think? That robotic voice is a big turnoff. Why do you use it? Who is your target audience? I'd strongly recommend you use a human commentator. I think this is your biggest problem. It just sounds so impersonal. )
2) If you're using SEO techniques, make sure the keywords you are targeting do in fact reflect the content of the video.
3) If you're using custom thumbs, make sure they too reflect the content of the video.
4) Make short videos (less than 15 minutes). The longer it is, the more the viewer will realise he'll never finish it and he'll quit earlier.
Note that points 2 and 3 above will increase audience retention at the expense of views, but that's not a bad thing.