Sometimes even 1 or 2 star caches can be akward. When you pick a cache and get to near ground zero, start to say to yourself 'Where would I hide a cache round here?'. Look at the hint and try to think outside of the box, or look for what may be unusual, or if an area has been disturbed recently. We found a cache recently where there were lots of trampled nettles.
Also, find a route where there are 5 or so caches, maybe a nice walk, then you have more chance of finding something than if you look for 1 at a time. Even if you don't find anything, you can still use the caches to find great walks or new places.