There is an area on TNet where caches are listed for your state. Start there.
Do a google search for those caches you think are close to you, or maybe in your own town.
Check newspapers for the time frames involved, search histories for the names involved, or the locales.
Remember each cache has 5 questions that need to be answered, or just one if part has already been found. The more of these questions you can answer from your research (don't rely on other sources), the more likely you will be on the right track.
Who?
What?
When?
Where?
Why?
Of those questions, Who is the most important. Once you have found out Who, you can usually find out when, Where, Why and What.
But if part or all of the cache has already been found that you are certain of, your legwork will be lessened, and all you need is a search/salvage agreement and/or verbal permission to search for buried objects on the land.