Privacy goes hand in hand with security. But what most people forget is settings and opt-outs. Let's take Android for starters, since that's all I use.
1) Your account with the ISP (internet service provider) like Sprint in my case, has settings and opt-outs & OPT-INS so be careful. You should log in online to make adjustments to everything allowed.
2) Your device OEM. Same thing as above. They all want a piece of the action. Here, you should seek to find respected third party apps, without ads. Paid pro versions, or I've found many free, ad free apps, usually open source, which I donated to. The less you use oem products, the less they have on you.
3) "Google"! Love, hate relationship. However, they offer more settings and controlled over your personal info now, more than ever. Explore these thoroughly. You'll be pleasantly surprised at just how much control you DO have.
4) Use a browser like Firefox that you can harden against all types of threats, especially making it more private. Aside from add-ons or soon to be extensions, they are giving it native tracker blocking as well as other tricks in development. Since you spend most time browsing, it makes sense that this be the most important app, and being able to customize it, is extremely important.
5) A VPN or Proxy for Security & Privacy.
Orbot, made by Guardian who make Orfox (Tor browser for Android) also allows you to proxy any apps connections thru it's use of the Android VPN protocols. ProtonVPN is a new service you should look at because they ate all about security and privacy. They offer ProtonMail too. Free accounts are available in limited forms. Tiered accounts are reasonable. Typically, free VPN's for Android are a mess. Be very careful in picking one of these. There is lots of information online, and many studies. Scary stuff. Paid version are usually better, but do your homework.
Privacy & Security take lots of time & work. Is it that important? I very much think so. I belong to several advocacy groups, EFF (electronic frontier foundation) Mozilla, Access, and more. I am in the fight to preserve encryption, and expand its use. I read research studies on all manner of Security issue's.
You get the idea. If we don't fight for these things, we will lose them. So use every tool at your disposal, and support those who make them available.