There are lots of posings with similar frustrations and technical answers to finding caches. These are very helpful and abundant so look them up.
As an alternative I offer my own approach which is to apply a little Zen philosophy:
Certainly, do your homework before hand and have acurate way points etc. But, then, approach the search with a "beginner's mind" and without expectation of finding the cache.
You will be out of doors and and be led to some scenic or unusual places. You may very likely be surrounded by the glories of nature. Drink in the experience of that moment! Even if you don't find the cache you have been rewarded!
As you close in on the cache be patient with the GPS unit and with yourself. The GPS is executing it's calculations as flawlessly as it can. Know that there are many factors outside of it's control and yours. Allow it the time it needs to contemplate the sky and the unseen satellites guiding you.
As you become one with your unit and with your surroundings (and with some practice and maybe, a compass) you'll come to know which readings are acurate and which are not. Observe your surroundings without judgement and you will soon notice likely spots for the cache to be hidden or areas that, though camoflaged with natural materials, have the subtle look of human tampering.
Undertake the search when you have time to focus on that activity alone. Embarking on a search without ample time will fill your mind with worries over where you need to be next, what's in the cache?, is the sun going to set? what will people think if I don't find this? Let go of extraneous thoughts and focus your mind and energy on the task at hand.
When you find the cache, do so with mindful gratitude. Many things and people have been involved with your success: The designer of the miraculous GPS technology, those who fabricated the container, the placer of the cache, the tree who's leaves and bark conceal it amd those who have left meager tokens of thier own life's path within it. Finding the cache connects you with all of them!
Have patience, Grasshopper. And remember that there is much more to the Geo-Caching experience than finding the Ammo-box!
"Now may every living thing, young or old, weak or strong, living near or far, known or unknown, living or departed or yet unborn, may every living thing be know happiness!"