We just started a week ago, and this is how we started out - with Google Satellite Maps in an urban setting. It has worked for the most part, but it does have its limits.
We tried to find a grouping of several caches in an "urban forest" here in the Twin Cities (Theodore Wirth Park, just west of Mpls), and our maps were seriously lacking. We ended up figuring out how to use the GPS on my wife's phone, but we'll have to invest in a regular unit at some point.
Another problem is that Google and other map sites can be out of date (say it isn't so!!!). We went after a cache near our home that was in a drainage pond. When we got there, we found the pond bisected into two ponds by a walking trail, and ultimately the cache was found here. Another time, we went after one that appeared to be in a parking lot. Whoops, someone forgot to tell Google about the new parking garage. I've since found another view that shows the garage, so we should be able to find it on the next try. If you're not completely familiar with the area (we just moved here, so that's our excuse lol), be sure to check a couple of satellite views (Google, Windows Live (including the bird's eye view), etc), and watch out for new construction, changes, etc.
As for actually finding them once you're at ground zero, you need to think outside the box at times, something we're still learning. The cache in the pond mentioned above was eventually found because we found another cache that opened our eyes (similar hiding methods). Read the cache page thoroughly. If something sounds like a play on words, duh, it is! Re-watch the ending of Star Trek II, and think in three dimensions as you look at that tree stump. If you're still having difficulties, let it go, and move on to another cache until the "aha!" moment arrives.
