On the technical side, THE most important thing is lighting.
As for the cameras you will find in smart phones, they are capable of doing reasonably good results, especially when the subject is well lit. If you can keep your mouth reasonably close to the microphone, the audio can be quite reasonable as well.
I would suggest you just get your phone and a couple of decent lights and try. See how it turns out and then you will see what you're not happy about.
You can then look at the reasons why things aren't the way you want and take steps to improve them. This is, perhaps, THE most important recommendation I could give, as you will learn how things work - or don't work. This will pay huge dividends as you go.
By all means come back here and ask questions - and we will do our best to help, but don't start out by looking to spend money on gear you don't know you need. Just jump in and learn with what you've got.