Keep it real simple. Look at the forecast, then team up with a buddy boat or boats. Then you can cover more ground and relay info on the radio if one of you finds the fish. Head for your targeted area.....West. Keep an eye out for birds on the horizon, as stated above. They don't always show where the tuna are at, but it helps. Look for birds congregating, diving, even sitting, as they may be sitting on a pile of bait fish. As you approach, do so cautiously. Spooking the birds usually spooks everything. If that happens, move away and watch what the birds do, then follow them.
Jumpers. Look for them "jumping". Or finning. Sometimes no birds needed as they will come out of the water. A good pair of polarized shades comes in handy. Also, as stated above, look for floating objects. Tuesday, we found a floating pallet....but no fish. This late in the game, it's a "run and gun" show. I like to cast 2 oz. swimbaits (able to cast them farther....don't have to get as close to the fish in case they are shy). If you DO get into fish, mark the spot on your GPS. Once the fish move (or go down), look in the same area for more birds (sometimes even a single) or more fish finning or jumping. Also, watch the direction the fish are feeding. Watch your "track" on your GPS as you will be moving away from the fish too. Then get back on them. If it REALLY dies, move. BUT, give the previous spot some time. Come back later in an hour or too. Usually, this is not necessary, but it can pay off.
The best resource is this board. Make friends, team up and hunt them down. Just my
. Hope it helps.