Like the previous poster stated "Have patience", but another thing that could be making it a bit difficult could be that you are using a TomTom, don't get me wrong they are great for what they are designed but they are designed for traveling by car not walking in the woods. When you start to get into trees and stuff like that they start to get very weak signals and bounce.
You also have to remember that when the GPS says that you are at ground zero that your gps could be off by 5 to 30 feet, as well as the person that placed the cache GPS could be off by the same. So you could be anywhere from 10 to 60 feet in any direction from the cache. Usually it's not off by that far but it could be.
I would recommend if this is something you really like doing and think you will keep doing it I would invest in a better GPS unit, a Garmin or Delorme etc... alot of units now have paperless caching built into them so you download straight from the computer to the GPS. Another thing to do is go caching with someone else that has been caching for a while and see what they do.