Regardless of flasher make, you will need to tweek the gain every time you change baits...say from a teardrop and waxie to a jigging spoon and minnow. Its a simply habit to get into.

Also, keep a battery charge level indicator handy while fishing if your unit does not have a built -in. As the day gets on and battery charge gets used up, your locator will begin to get funky if you don't re-adjust the gain and the IR. Most units will work optimally with a fully charged battery but will start show you "ghost" images, maybe even telephone poles, when the batteries are below 40%.

When your ice is over 24 inches, its probably best to drop the transducer to a depth that is slighly deeper than the hole itself to avoid echoes off the walls of the hole. I do this and just slide the unit to the side so the cable is against the wall....if I get a decen fish on I just slide the unti away pulling the ducer up to almost the top of the hole.

One thing that is hyper important is to take care of that transducer when its not in the water. Just sticking it back in the tray after use doesn't offer much protection. I wrap mine in 1/2 of a terry-cloth wash cloth, then fasten a rubber band to hold the wrap on it. Scratches can wreak havoc on a ducer face if they are wide or deep enough. Ducers are NOT cheap.

Keith does a good job of summary here. I own Marcum and Zercom. I'd go so far as to recommend the round flashers, but will have to say pass on those towers. Eagle makes a nice flat-screen ice unit using military grade liquid crystal that stands upp to cold temps and these work very nicely, but the round, traditional flasher will afford the angler the best of target seperation and fishing ease.