The thing a lot of parents do not realize is that it is very difficult if not impossible for D1 schools or for that matter any college/JC to watch your son play high school baseball, why? Because they are playing/practicing at the same time. The most important thing for good HS player to do is to get out there during the summer. I believe that there is no such thing as too much exposure. It is very important to play on the best summer team possible, one that is coached by someone who understands how it works and takes his team to the right events. In addition it is important to attend individual events such as showcases to get your self on the radar screen outside of the geographic area you reside in. I believe that if you are a strong HS player there is a college out there that you can play for, it than becomes a matter of making the connection. There are many avenues to accomplish this .... camps, showcases, national tournaments, writing letter/phone call to coaches. For sure the elite nationally ranked players will be recognized, but even those players need to get out there so scouts/recruiters can cross check them against the best competition. If you are seen only once by national cross checker you might have a bad day and that could be a deal breaker, on the other hand if he gets to watch you a few times chances are he will see you at your best.
Personally my son spends much of the summer traveling with his southern California travel team. They do Perfect Game WWBA, BCS, Connie Mack, USABF. In the fall he plays scout ball and goes with his travel team to Arizona Fall Classic and PG Nationals in Jupiter. I am fortunate in that I can afford to send my son to these events that provide tons of exposure, but most importantly they provide some of the best competition available which helps him to improve.