To have an effective video lecture, you need to stage your videos properly. First, you need to have an area where you can record without interruption from others. That is essential. Second, you should make sure your lighting in the area is sufficient for the video. Third, you should make sure that your appearance and your setting are sending the message you want sent. If you want a casual video, set the stage for that with your appearance and location. For something more formal, make changes.
See to see this demonstrated in a video format, see this video by Dr. Pope: https://youtu.be/DZlDgstX5Nc
In recording video lectures, sound quality often reigns supreme. While video quality will vary depending on the streaming level available to a given student, the sound's innate quality will often carry through much more clearly on a poor connection or a great connection. As such, good sound is important.
For your purposes, you'll want to make sure that the space you're recording in allows for good sound quality. A good starting point is to simply not record in a room with excessive echo. Bare walls and floors often contribute to echos, so places like a bathroom are terrible choices for recording lectures for the same reasons they're great choices to create a lively sounding guitar track–the bare surfaces create competing echoes that will many times come through on your recordings.
A dedicated microphone can go a long way towards helping your content sound good. The microphones that come with most laptops and webcams are too far from your face and pick up too much of the surrounding sounds. A simple USB mic is often better, even a headset mic. If you wish to go into higher quality solutions, there is a point where price and effect become unmatched. Yes, you could spend 3k to buy an NPR-quality microphone, but the quality difference for your students isn't going to be much more than a $120 microphone at the end of the day. You're not going to be mastering your tracks and using expensive preamps, so just a decent mic works well enough.
Listen to your recordings, and see what you can hear that shouldn't be there. Sometimes just a simple curtain behind you or recording in a space where there is low ambient noise can be enough. In a worst-case-scenario, you may need a microphone that is really good at rejecting off-axis sounds.
While you might try to wing a lecture in a face-to-face classroom, you'll find that is much less useful in the online space. Without an interactive audience, going into a lecture without a structured plan is not a great idea. (And generally, you should plan lectures, regardless).
Think about what you want to cover, and how you want to cover it. Break the content down into discrete chunks that you can cover in individual videos in a series, allowing students to progress at their own pace in small periods of time if their schedule isn't friendly to binges.
PowerPoint slides or the equivalent can be useful to help you stay on topic as you present, and they often represent a format that students are already comfortable with at the start of things.
While you may be able to wax poetic for days on your subject, your students often do not have the same attention span. Online and remote courses can be a challenge to students, especially when lectures are recorded and linger for an hour or so. Try to keep your individual videos below 10 minutes, with 5 minutes being the sweet spot that many identify. Yes, this can be difficult, but you'll find that smaller, more digestible chunks work well with students.
At the very least, try to limit your videos to a single goal if they will be longer. For example, a longer video on how to apply a filter in Photoshop might be excusable if you go through the entire process during the clip.
In a last-ditch attempt, you can also simply slice your extended lectures into five-minute bursts after the fact. This can be as effective as simply making a bunch of shorter videos, and may be more natural for you.