Rabbits are tough to spot but not impossible. First hunting at high noon is a exercise in futility, hunt early and late like you would for deer. Second slow down, slow down, slow down, most folks try to cover way too much ground far to fast. Focus on "hides" brush piles, thick scrub, overhanging tree branches especially pines. Scan for horizontal shapes not necessarily rabbits, horizontal lines are very uncommon in the plant world and shapes are far easier to pick out in heavy cover than critters. Not at all sure what your weather is like but some of the easiest bunny bustin is done after a sudden thaw, white rabbits kinda stick out in a brown back ground. Work in teams a scrimmage line will often move rabbits when a single hunter wont. Pay attention to local population trends. Rabbits run on a about 4-7 year cycle, right now you'd be hard pressed to get a bunny in my neck of the woods, thats why I'm driving an hour east this weekend. Get low, I spot more rabbits on my knees looking under brush than any other time. And practice you'll start spotting them allot more when you get a better idea of what visual cues to look for. That's what immediately came to mind sorry it's less than organized.