My kids have a little craft box full of things to stick to paper to make pictures. Due to flattie rigs there are no longer any sequins left. (SSSHHH they maybe listening)
I, like many put a sequin between every bead above the hook. Works for me.
Great advice already but also consider where you are fishing. If you're fishing a rising tide over mudflats with deep gulleys then consider fishing a long trace with your hook/sequins/beads but with a large pierced bullet above it stopped with a swivel. I assume you're using a light rod and cast into the gulleys but allow your rig to move about. If it's snag free then keep it moving slowly with the occasional long 'twitch' to pull it up off the bottom. Flounders just love peeler crab and have been known to swallow one intended for Bass. However it is one occasion when I will cut a crab up and wrap it well with bait elastic to make it more 'flounder-mouth-friendly'!
If you are fishing a mark with a muddy/sandy bottom, known to hold Flounder, then consider using a large baited spoon on a spinning rod. Cast it out let it sink , then 'draw' it up into the current about 18" before letting it drop again. My Flounder spoon is about 2-3" long and white in colour with a single hook trace of about a 1' attached to it. Once I had a metal, white enamelled one which had good casting weight, but the only ones I can find now are white plastic which need added weights (I still use small spiral leads which you can attach without having to break down your rig - rapidly running out of them as well!!!)
Instead of sequins try puttting on what I can only call mini-spoons - about 1/2 to 3/4" long. I've just found them and they're going on damn near every rig I make irrespective of fish species targeted!!!