The Hot Spot flasher works and silver with chartreuse or green is best, tail leaders are dependent on how much control you have over the trolling speed of your vessel. The post are all leaning in the right direction in that slow is the key to successful chum harvest. Likewise they all said to go small I find this to also to be good advice and would suggest only that you take it a little further and use a bare hook or if you can't get your mind around that then take any hoochie and cutoff 3 or 4 of the legs and and with wire or kevlar thread lash the legs to the hook The entire lure need be no longer than the length of a 5/0 siwash hook. Hope this helps you get some chums when they are a long way from the maddening crowds.
Oh by the way if you are using a downrigger snap your gear on about a fathom apart the more the better take as many as your boat will carry schooling chums like lots of flashers you can actually get the entire school to follow you on a straight tack if your speed is right