I have an idea on a painting but need your advice please....?

i have recently started to do abstract paintings using acrylic paints, and i have come up with the idea of footprints on canvas using my own feet and my husbands feet!! i have decided that this would be great on canvas in our bedroom but i need a couple of tips. i have decided to do our footprints in black because this will fit in with the theme and colours of our room, but i am not sure of a background colour? could i use a normal emulsion paint in a light colour or do i use acrylics? once the footprints have gone on, what do i use to seal the colour all over the canvas? have you any other tips to make my idea even better? i want to do this for two reasons, one reason is because i think that this will be an unusual but lovely keepsake, and the other reason is that i want something different but personal to us. i would be very grateful for any of your thoughts or idea's on this. thank you so much.