If you want lower guitar string height, my first piece of advice to you is to bring it to a competent guitar technician. Why?
Guitar technicians are smart, savvy people who are excellent at addressing wide range of playability issues on guitars.
You'll learn a lot from asking them questions, and you'll lower your guitar string height.
The rest of this post goes over all the advantages of befriending an awesome guitar technician. Let's hit this!