A software application that will enable you to make an AV recording of your singing. Iphone and Android have built in apps that will work fine there is a host of open source and free software. (see below)
Don’t play the music into the room, use your headphones or earbuds with a mic in them, carpeted areas are best.
If you have a nice mic and a recording system use them.. but it’s not necessary
Listen carefully to be sure you are in tune
Light your face and wear solid colors with no logos or patterns