First off let's get the technical stuff out of the way. For some this is very common for others this may be new to you - and that's fine. This is something I learned as well when shooting video. Let me also be clear that you do NOT need an expensive camera set up. You just need to know how to properly set up the tools that you do have.
What I would normally do is kind of just set up a camera and then get in front of it and start rolling! But there's a lot more to it than that. There is a few things that can help make your video pop a little more.
First thing is framing. You want to have everything framed correctly. You also want to have proper lighting and make sure you're close enough for audio but for sure make sure you are framed correctly.
Knowing the rule of 3rds:
What I like to do if I'm filming on my camera or on my phone is I like to bring up the grid.
Depending what phone you have you can go to your menu and select in your options and to turn the grid on. What this does is it will have two lines in the video vertically and two horizontally. Therefore you end up having nine squares in the video. When I am shooting videos that have just me talking I will make sure to have my top horizontal line going right through my face/eyes. Then from there I make sure I am centered within the frame. That way everyone's eyes seem to want to look at you as the subject. If you put yourself way off center then people's eyes get distracted and never seem to want to focus on you.
Now that you have your grid on your phone make sure that your lines are straight with the horizon. It doesn't give it a very good look if you have your phone tilted. Having your grid helps you to keep track of all of this and give you better looking videos.