when you think there is no where else to look,,, look back where you started looking,, you were probably correct,,, just not "there". Im fairly new to this as well, but have a keen sense,, and have no DNF's. If you aren't sure about your target, find more resources, and/or, ask the person who placed it for a hint. Two of the caches I FINALLY found after multiple visits, were due to others like myself and you, that are new, and learning some of the SNEAKY AND UNDERHANDED tricks that some of these owners are used to.
Anyway, don't give up. It's actually a "kick in your own butt" when you find something that you have looked straight at a couple of times.
Stephan