There are many ways to begin a treasure search and I am going to show a method that works well for me. This is a way you can begin a treasure search without a map or a story, and if your lucky, find a place that hasn't been disturbed by treasure hunters. There are a lot of treasures still in the ground simply because people don't know they are there.
The first thing to do when considering a place to look is to pick an area close to where you live. This allows you time to work a site without having to spend a lot of time getting to it. Go on the internet and look at topo maps in your area and note the creeks, rivers, and hilly areas.
Once you have an area in mind, find all the old maps you can. Also get a modern topo map for that area. The older maps should show trails, wagon roads, ferries, railroads, towns, etc. When looking at the old maps, note where roads and trails would cross the creeks and rivers. These were important places then because horses, mules, and people needed water, and this is where people would stop to rest while watering the animals. Also, if some of these places were aways from a town, people would stop and camp along the creeks and rivers close to the crossing.
Note on the old maps the roads and trails that lead out of a town. Follow those roads on the map to the first creek and river crossings out of town. Note those spots. Then refer to the modern topo showing elevations and see where those spots are located now. Look for the high side of the crossings and also look around those crossings for a mile or two and note any hills or prominant areas. These are landmarks, and especially if they stand out and are visible from the old trail. Back in the old days, trails followed landmarks along creeks and rivers.
Once this is done, pick the landmark that is most prominant and closest to the creek or river crossing. The ideal location is the first crossing several miles outside of town. The reason for this is that people in those days, if they were carrying any money, would stop at these landmarks just before town and hide their money, save what they intended to spend, because they didn't want to be carrying it around town. It would be the same way if they were camping along a creek or river in unknown parts. They would stash their money and valuables closeby in case of a robber or theif.
Another thing to consider about these landmarks along the trails, is that outlaws would congregate there and sometimes have a stash spot laid out even before a heist was made. This made it possible to hide the loot quick while on the run so the weight wouldn't slow them down. They would then come back, if they were lucky, and retrieve the loot when things cooled down a bit. Always look to the high spot, because this was easier to defend if they needed a little more time to stash. It is way easier to shoot downhill at your pursuers than to fight it out on level ground.
When a stash is made at a place such as a landmark, they usually would mark it by using their names or variations of it instead of obvious treasure symbols. In this name will be the coded directions and distances to the stash. When aproaching the landmark look at the area that first grabs your attention. This could be a huge boulder, grouping of rocks, or an interesting feature. Look all around the area and see if you can locate a name or other symbol. This is usually where a treasure search will begin.