I know a lot of ISPs will not only access and sell off data, but their security within these companies is lack-luster at best. I am looking for ways to make my internet more secure not only from outside threats but from my own ISP data harvesting me.
Disable remote management features which in and of itself will secure you from hackers. Most people know to use VPNs so it is not really worth mentioning. Outside of those things changing default admin password should be done ASAP. You also want to switch you DNS to 1.1.1.1
You also want to switch you DNS to 1.1.1.1
This is the easiest thing you can do to prevent your ISP from accessing your browsing history. Learned about this years ago. It isn't 100% protection but it makes it harder for them and they just don't bother when you do this.