If you’ve ever been on these before, try to remember ANY structure you know of. Weeds, isolated patch of gravel, a single crib/bit of brush, hell an old tire. ANY significant break, point or hump…”significant” can be as little as 1ft. If these are plain shallow lakes, any bit of variation is probably going to get used by fish even if they move a lot. If they’re new water to you, well, Triplea said it. A lot of holes…I know that’s not what you want to hear, sorry. Though, I’m not above paying close attention to any old holes others have left. A few leftover waxies or minnows on the ice, lots of stomped down snow around one hole in particular, blood on the ice can all be indications that fish were caught there. One thing about ice fishing, it’s hard to hide where you’ve been-like the proverbial trail of bread crumbs we leave out there.