Firstly, this question sounds pretty clearly self-serving, like saying "I want people to like me more; how do I make them like me?". Secondly, school is a business, much like other businesses. When a company makes a product, of course the company hopes the market will "appreciate" the product. There are many marketing strategies used out there, but the long-term viability of a product requires that it provides clear value. Without that value, prospects cannot be expected to appreciate the product. In the case of high school, most students are probably aware that the product is not being sold to the students but instead to the parents. Hence, students are not the customer. Since students are not the customer, and since students had little to no say in the product's design, getting the students to appreciate the product is going to be very challenging.
One approach is to make the students believe they are the customer. You might, for example, use a bandwagon strategy wherein you explain that "There are many happy students from years prior who have attended this school and are now enjoying a life of success and freedom".
Another approach, which would be more honest, would be to actually make the students into the customer, such as by designing the curriculum around their needs and aspirations while providing a clear value that cannot easily be found elsewhere. If you are to be honest with yourself, this is the only noble approach. If a school cannot provide clear benefits that a student cannot find outside of school (such as on the Internet or in books alone), then that school is not doing its job. Sure, there are many types of rhetoric and trickery that can (and often are) employed by schools and governments, but these are nothing to be proud of.
In short: Provide a unique and worthwhile opportunity with a benefit that can be seen clearly. Engage the students in the curriculum -- make them the customer.
PS: While a bit off-topic, I just remembered a music video that critiques some of the curriculum focus in the recent if not current school system. This video had no bearing on my answer here as I only remembered the video afterward, but its topic is related enough to be worth mentioning here.