Still littlesnitch is really awesome for the privacy conscious users.
To achieve the best security, you should disable most bultin rules or customize them yourself.
Could you point to a source which would help me educate myself?
But most other processes are easy to block. The first thing you should do is check the name of the process. If it is something like iTunes, you need to ask yourself if you want iTunes to have Internet (do you want Apple Music/radio, wifi sync, and the iTunes Store? If not, just block all ports/servers for iTunes. If you only want Wifi sync, enable connections to the local network only (best do it manually in the rule settings). If you want iTunes to have Internet, I'd allow port 80 and 443 to apple servers and apples CDN (you will end up having ~15 rules, just allow the servers as you see fit and when prompted). Since iTunes is from Apple, it uses some system services to communicate with iCloud additionally, by default they are all enabled and you don't have to do anything. All essential system processes are allowed by default. I personally disabled most of them since I don't need most of them. Let's have a look at gamed. gamed is a system process to communicate with the Game Center services. If you want Game Center to work, you will also need to enable this process. You can learn that by yourself if you click at the question mark on the bottom left corner when an alert pops up. It shows additional information for all system applications, and most popular apps. If it says that this process is needed for Game Center but you don't play any games on your Mac, it is safe to disable.
You can do that for all processes and eventually work out a list with trusted services and applications. I personally often only allow some applications Internet to port 80 and 443 and only if I know the apps really need it. If you don't trust the app at all, you should update it manually (by downloading the newest version on their website).
Also, Microsoft really needs to clean up their domain usage, because it takes 999 permission rules to run Office.
The issue with this is that the DNS settings only apply at home. And most mobile devices totally ignores the DNS settings as well, using the one provided my my carrier instead.