Use what they can't get. I have several acres of corn and so do my neighbors, so even if I took all my corn off they can still find it in ample supply. They will however, still eat corn bait if they pass it. I use molasses in my corn to draw their sweet tooth, but I have never gone wrong with cut apples hanging in the apple trees. I keep them in the apple trees so it seem real enough to them. I also mix a paste of apple butter, peanut butter, and oats. I put oats in it to keep it from freezing solid when I put it on stumps.
We use apples also the trick we found was to put out only 3-4 apples each morning ,late in the day apples encouraged them to come at night and so did to many apples so we started just putting a few out every morning this gave us the best results.
When placing a trail camera don't just look for a well used trail. What you want to do is look for a freshly used trail off by itself that goes from a north facing ridge, thick forest, brushy knob or some other similar bedding area to a food source. Don't forget water sources. Especially in the summer months the deer need water so look for a good trail going down too a creek surrounded by thick cover and place the camera 100 yards up from the water source.
Scent control is very important...