Shoot in Landscape mode
Make sure that you shoot with your phone horizontally in landscape mode. Most platforms such as LinkedIn, Youtube and Facebook are optimised for horizontal videos. This means that your video will look better on these platforms and more professional. There are some exceptions to the rule, such as creating Instagram stories and TikTok videos where the platform supports vertical video.
I would recommend using the front-facing camera. The quality will not be quite as high as the rear-facing camera, however, It will allow you to see what you are doing much more clearly and help you to frame yourself.
Use a mobile tripod
If you have a mobile tripod, locking off your device will ensure that there is no unwanted camera shake or movement in the shot, making it look more professional. These can be bought cheaply on Amazon. Alternatively, there are DIY options that you can use to prop your phone up, such as Lego! Please make sure your device is secure and is not at risk of falling and breaking.
Lighting is one of the most important aspects to get right.
Your phone will automatically expose based on the other light in the image. Make sure that your face is well lit. The simplest way to do this from home is to use natural light from a window. Ensure that the light is hitting you from the front or slightly to the side. If the light source is behind you, it will create a silhouette, and your face will be in darkness.
Try to avoid harsh direct sunlight if possible.
If needed, you can also use additional lighting from household lamps etc. Try to use bulbs with a 'daylight' colour temperature to keep the look consistent.
Frame yourself in the centre of the shot. You should have a small amount of space between the top of your head and the edge of your frame.
Make sure that your surroundings are clean and tidy. If possible, try to avoid filming yourself up against a wall as this can look very flat. Having some background visible will create a more dynamic-looking shot.
Also make sure that you check your background for distracting items. For example, a plant that appears to be growing out of the side of your head.
For an even more professional look, you can use a natural frame, such as sitting in front of a bookcase.
Audiences will tolerate a lapse in picture quality much more than bad sound!
Make sure you record in a quiet environment, preferably somewhere where you will not be disturbed that doesn't have too much ambient noise such as traffic noise, computer fans etc. If you can, use a room with a carpeted floor, soft furniture and thick curtains. Empty rooms with hard floors will produce a lot of unwanted echos.
If possible, use a cheap external microphone. This is not essential but will improve the quality of your audio. If you have one, or want to pick one up from Amazon, make sure that you choose one that has the appropriate connection for your device (USB-C / Apple Lightning / 3.5mm jack).