Its all about experimentation mate...
When buying jellyworms, I've found the best colour to be jet black with a fire orange, red or bright pink tail. When using rubber eels, I've found the best colours to be jet black, fire orange, red, pearl white and a white/blue mix.
As said its best to experiment with what you buy till you find the colours that fish best for you, so buy a mixture off colours to try, and see whst happens. Last year when spinning with eels/jellyworms off shields pier, I had coalies, codling, pollock and Mackerel.
I would suggest popping into Reelsport on Dean Rd, south shields, as he has a vast selection of lures, spinners, sidewinder rubber eels and jellyworms to keep you right, all good quality gear and brands to, as I've used successfully.
Hope this helps mate.