Need advice. First project!

I found this mosaic tray online that I fell in love with and I love everything creative, painting, diy everything you name it if I haven’t done it I will you can bet. So I thought I’m going to make one and here I am. I bought a wooden serving tray (teal) with gold handles and some iridescent tiles to get the same feel of the one I saw online but not trying to copy it. I don’t know if I need some complimentary colors or larger and or different shapes and I bought black grout but now I’m questioning that. I’m attaching pics of the tray I found online that made me want to give this a go, as well as the tray I am going to use and pics of the tiles I have so far. All suggestions are welcome and no I haven’t figured out a design yet either…..I feel like I need some larger tiles and maybe some shapes but do I do iridescent or what color would compliment the ones I have. Thank you all!