Get some of these in 200 and 300 gram.
http://h4ljigs.com/Goober-goob.htm fish them 200-300feet down. If the current is bad fish the 300. If not, the 200 might be enough. Night time is much better. The cudas can wear you out though. NOT working the lure within 100ft of the surface can help reduce the number of cuda cutoffs. Lots of good ways to catch tuna but for a first timer just after blackfin, this will be the most productive.
Jigging can be a lot of work. If you just want to bait fish and cant really catch your own bait then order some of these, hook them through the nose with a 6/0 mustad demon circle hook, stick a toothpick through them just behind the wings to pin the wings open, and drift them out from the ship.
http://www.baitmasters.com/store/shopdisplayproducts.asp?id=45&cat=unflyfish Much more likely to catch yellowfin like this and its probably the easiest way of all to tuna fish.
For casting go with the mini-komodo
http://www.oceantackle.net/popping.html or Maguroni
http://www.oceantackle.net/maguroni-lures.html
What area are yall working?