Choose a simple background
The key is; you want to stand out from, not blend into the background. So, try to find a wall or landscape that allows you to be front and center. If you are doing your audition in front of Picasso's Guernica, where do you think the focus in going to be? What about a sunny day at a busy beach? A Maserati shop? Your child's day care? I think you get the picture. Keep in mind what clothes you are wearing, too. A terracotta colored shirt in front of a red-brick wall; well, visually you may as well be behind the wall.
You don't need to hire a cinematographer or stage-lighting designer to create the perfect ambiance for you, although my friend Kenny would be happy to fly in for the right price. You just need to be seen. It's fine if there is enough light for the casting director to see the glint in your eye. Luckily the smart phones today usually have decent cameras that can capture images even in fairly low lighting.
A key thing to remember, and believe me I've seen enough self-tapes to say this, keep the light in front of you. Unless of course you are auditioning the back of your head. But, what are the chances of that?
I've rambled on a bit about the visual background. Now, what about the aural background? Where ever you've decided to do your audition, it should be quiet. Need I say more? If you live next to the highway, it's probably a good idea to close the windows. If you have a talkative Siamese cat, they seem to sense you are making a video, it might be a good time to ask it to visit the neighbors. And if you have someone holding the phone or camera remember, they are closer to the microphone. If they are feeding you lines, who is going to be clearer? Try to set the phone down and have the ‘feeder' stand behind it at good distance. They can start the recording then step back.
These three simple tips won't guarantee you the job, but, it will guarantee the audition is watchable.