now we're talking
hi longfin, welcome to the forums. I've got a special interest in flashers, and have been trying out all sorts of different ideas. in my opinion, the bought ones are guarenteed to work, but then you miss out on trying new stuff out for yourself. sort of like tying your own flies.
i've got a small foam filled float made out of a 500ml soda bottle that i hang the flasher off.
usual technique is holding the line in my hand, working the flasher up and down. if i do a dive, i let the float go. the problem is that you need to retrieve it, especially if you end up chasing a fish, which is a bit of a pain, but it keeps you tangle free.
about where to put it, if i'm covering ground i only attach mine to my floatline if i'm not using it and bored of dragging it with me. this is because it ends up way behind you and its no longer serving its purpose.
if i'm doing drifts and not moving very much, i have it clipped to the line, about 15m from the gun, depending on the depth the flasher is at (about 12m). the advantage of this is you can dive down to the side of the flasher and level off at the same depth. the float is small enough that it just gets dragged down without much resistance if you do want to go deeper.
the whole lot can get a bit tangled if i'm stringing a fish i've just shot, but thats because i like to keep my gun close to me, so everything is in the same area. having thick mono for the flasher helps if you get a bit tangled up.