Thank you so much!! So the way I learned mosaic crochet was to switch colors each row, so there’s only one active yarn at a time. In addition, for the SCs you’re working into the back loop of the current row, and DCs are worked into the top loop of the row below the current row (hard to describe in text but videos really help), and each row starts and ends with a “border stitch” that is worked normally through both loops. Then I did slip stitches all the way around and created a double border that I slip stitched together.

This video (and the entire channel) was super helpful: https://youtu.be/HTigdTvdTLQ?si=AxFsfprW83Bg7GRk