Been making little embroidered bird brooches for a few years now and thought I'd share what actually makes the difference between a floppy mess and something you'd proudly pin on a coat. First big one: use two layers of felt even before you add the backing. A single layer distorts badly once you start dense stitching, and your bird ends up looking like it melted. Sketch the design on the felt with a water soluble pen, not pencil, becasue pencil never comes off felt properly.
For the shading on something like a pigeon's neck, don't try to blend threads like paint. Just pick three or four close shades and let them sit side by side in short stitches. The iridescent look comes from a shiny thread in green and purple worked in tiny random patches, not from anything fancy. Beads around the edge are the easy part but people rush them. Anchor every single bead with its own stitch, then run a second thread back thru the whole line to straighten them. Otherwise you get gaps.
Last thing, and this took me ages to figure out. Do the blanket stitch backing before you trim the shape. Stitch through both layers following your drawn line, then cut close to the beads afterwards. Cutting first means you're always fighting frayed edges.