Lock the float with shot or float stops so the strike actually moves the hook. Put most of the loading at the float so it casts. Use one or two small droppers to settle the bait and to give you lift bites.
For a pellet waggler, drop the droppers (or use one small shot), shorten the depth, and lock a dumpy loaded float. For canal roach, go the other way: light insert, fine wire hook, and enough bristle to see a lift at 20 yards.
Components
Waggler 2–8g, float stops or locking shot, bulk, 1–2 droppers, hooklength 0.10–0.17mm, size 14–20, mainline 3–6lb, appropriate hookbait.
How to tie it
Thread stops or locking shot, float, more locking shot. Bulk. Droppers. Loop to hooklength. Plumb up. Set depth. Feed, then fish.
Common mistakes
A sliding float you forgot to lock. All the shot under the float and none telling you about a lift. Hooklength stronger than the mainline on a snaggy far bank. No plummet.