Longer videos for sure. You'll get more watch time that way. If you make a 3 min video and you have 50% of video watched, you only get 1 min and 30 seconds on average, but if you have a 10 min video with only 30% of video watched you bank 3 mins on average. YouTube prefers you hold attention for longer. The best way to hold viewer interest is to make longer videos and do these things:
1) hook them within the first 15 seconds by establishing the purpose of the video, or clipping the most interesting part of the video in the begging. Personally since vlogs are more of a story, what I'd do is edit your videos like a novel. Beginning, climax, conclusion. Establish the setting, build to the most existing part of the day, and then conclude the vlog/day.
2) Provide new substance to the viewer. Often I see videos that are just recycled content from another video or mundane content that no cares for. Since you're a small youtuber I don't expect you to make videos of you riding jet-skis in Dubai lol but you shouldn't try and elevate a mundane video to seem exciting because it never works. Honestly, vlogging is really hard because you have to already have something exciting going on to film. I'd recommend trying different types of videos to bring attention to your channel first, and then slowly start to introduce vlogging when your viewers are curious about your life.
3) Work on audio as much as you work on video. Video isn't just a visual medium its a auditory one as well. Small things like your voice being too low, or a constant rumbling in the background can turn people off.
4) Lastly, Be unique. I see from your video you've taken a lot of inspiration from Casey Neistat, especially with music choice and transition shots. Those are great, but try and inject more of your own creative ideas into your vlogs. Why would someone watch your videos if they can just hop over and watch Casey? Give em a reason to stay.
Hope this helped! Good luck!
