Many mobile phones these days work great for recording video. Whatever camera you use, here are a few things to keep in mind while you are filming. Don't forget to check the audio levels and make sure you can hear everyone clearly!
Shots and Angles
Frame your subject wisely. Guide the user's focus.
You can use a tripod to keep the camera steady.
Explore different shots. Notice the effect they have on the scene.
If you are using a smartphone, make sure you are holding the phone in the same way for every scene (horizontally is probably best).
Make sure you can see everything clearly.
You can alter the lighting to reflect the mood of the scene.
Check out this site to see the effect of different types of lighting.
Bring in additional lights if necessary.
Utilize natural lighting when possible.