You should always check your shot before you press the record button. And there’s quite a lot to check. These will be second nature to pro filmmakers, but when you’re learning it’s easy to get them wrong: you might get the shot size right but forget to check the focus.
First, check the settings and the sound.
Which angle will give you the best view of the subject?
Could you improve your shot by moving around the subject, or using a higher or lower camera position? Don’t just shoot everything from the same position.
If you’re shooting other shots of the same subject, the angle should be different for each one. More about camera angle
Watch out for distracting backgrounds that draw attention away from the subject. It’s easy to miss what’s happening in the background when you’re concentrating on the main subject.
If possible the background should add atmosphere or information.
How have you arranged everything in the shot? Is the subject in the right place in the frame? Is the camera lined up properly on what you’re filming? What’s happening at the edges of the shot? More about composition
Can you improve the shot by moving closer or further away? Don’t just shoot everything from the same distance. If the shot’s supposed to be a closeup, are you close enough? Is the shot size different enough from the previous shot? More about shot size
Is the shot correctly exposed? Can you improve the light by using lights or reflectors, or filming in a different direction? Is there too much (or too little) contrast? More about using light
Is the shot sharp where it’s meant to be sharp? More about focus and using the lens