Oh, right, you're going to fly an amphib... That adds two more factors: a useful load of bugger all, so it may not even be two people and full tanks. But, more critical, commit these words to heart: "Wheels are down for landing on land" or "Wheels are up for landing on water". Somewhere between downwind and base, you are responsible for looking at whatever landing gear position indicators are there, and after considering the landing gear position you observe, say the appropriate phrase, then look out the windshield, and confirm that the intended landing surface is what you just said it should be.
When I train amphib pilots, I'll let them forget to say the correct phrase once, and do it for them. After that, if they fail to say the phrase (accompanied by a meaningful check), I will call a panicked go around on short final - to purposefully scare them (and I actually make them go around, regardless of gear position) - just so they get it. Because no matter how badly I scare them, it will not be as bad as crashing in the water (ask me how I know!).
I extend this discipline to every retractable I fly, which includes wheelski aircraft. It's just good for pilots to do. When you turn up for training, and demonstrate to your instructor that this is normal conduct for you, the instructor will gain confidence in you immediately. No matter what other system or checklist there may be with the aircraft, the use of the phrase is your personal discipline which you use for you, to prevent you finding yourself floating (or drowning) next to a sinking plane.
That reminds me....I'll post my manifesto about lifejacket use from last summer next....