I don't know what you should do but I will share my experience with you.

I purchased an Android phone because it was about as cheap as any other phone. As a new Android "owner", I explored and tested the device "as is".

I proceeded to test the hardware. I checked that the microphone, speakers,camera, touch screen, cellular and wifi radio worked as advertised.

I continued by testing the default apps and studied the various settings for each of them. Any time I came across an app that required a sign-up or sign-in, I would close it and move on to the next app. I signed up for nothing so I've never downloaded or subscribed to any additional apps or services.

After a few weeks of real world testing, I turned off the wifi and rarely used the phone for any Internet services. It's nice to know that I can use it to access the Internet, I just don't feel that it's necessary. So I don't. I just use my Android phone for ordinary cell phone usage.

From the observer's perspective (Google), I am someone who is aware of their services but not interested. The observer loses interest in me. After all, what can you target advertise to an uninterested party?

The only observer left is the cell service provider. They are a necessity for the phone's primary function. That's the deal you signed up for. It is to their best financial interest not to creep me out. It is to my best interest not to use the service excessively.

I think the worst thing to do is use the phone for Internet services. I don't believe that adding any new apps will improve your privacy, they only trade off the risk to other potential observers.

I think the second worst thing to do is use the phone for Internet services while trying to maintain an alias or anonymity. Eventually, your anonymous/alias persona will accurately reflect and reveal your true identity. It would be like concealing your identity with sunglasses with an ID badge hanging from your collar.

My approach might not be right for you, but it works for me. Good luck.