Most of the time perch are more than happy to pick worms up off the deck. The only time I really resort to popping them up is when there is leaves or weed in the swim, as that can adversely affect good presentation.
When that’s the case, I simply hook the worm through the head and inject a tiny amount of air into the tail. I still want the worm to sink, but really slowly, and doing it like this means that on the bottom the tail sits up like a cobra ready to strike, making it visible and enticing to a hungry perch.
A word of caution – if you are going to inject air into worms, make sure you work on a hard surface. Accidentally injecting air into your bloodstream is extremely dangerous!