The following is a step by step guide that you can follow in getting started with your new DeGoogled phone.

Unbox and Power Up Phone
 

1. Ensure that you have received all the parts - phone, charger, cable, sim card tray removal pin.
    
2. If you have a SIM card to install, now would be a good time to do so.
    
3. The phone should have some level of charge, however, you can always plug it in to be certain.
    
4. Power on the phone - Note that a typical De-Googled phone will give you a message at startup to say that the software cannot be checked and that you should lock the bootloader.  This is totally expected, however, DO NOT attempt to lock the bootloader as it will cause problems.
    
5. Eventually you will see the LineageOS logo appear and shortly thereafter your phone will be ready for use.

Initial Setup

1. Check that your phone has connected to your mobile provider (if you installed a SIM card) – you could try making a call.  Or, you could go into Settings -> Network and Internet to see if your mobile network is indicated.  You could also just look at the logo at the top of your home screen to see if connected.
    
2. WIFI - If you are connecting to WIFI you could set that up now.
    
3. Setup VPN - If you do not have VPN on your home network you will have to install your VPN of choice on the phone.  One option would be ProtonVPN (its free) which you would get from the F-Droid store (which is installed and ready to use on your phone).
    
4. Congratulations, you are now securely connected!

Additional Setup

1. Usability Options - You may want to adjust some of the usability settings at this point (or you could wait).  Going to Settings -> Display -> Advanced will allow you to update the screen wallpaper and set desired font sizes etc.  At Settings -> Sound you can adjust a variety of sound volumes.  The Settings -> Security section allows you to setup your screen lock and fingerprint access.
    
2. Contacts - Setup your contact list by way of the Contacts app.  You could start by manually entering a few contacts.  If you have a big list from a previous phone you will see there is an option here to import from a VCF file (you would have to export your contacts from your previous phone to a VCF file) – maybe do the full list a bit later.  Another option (which is perhaps more secure) is to download/use the OpenContacts app from F-Droid.
    
3. Email – Your phone includes the standard Email client (Email app).  The K-9 and/or FairEmail clients will also be installed (you can use any or all of them).  Assuming that you already have an email account (or perhaps a few) you can set them up within these email client programs for easy access.
    
4. Messaging – The standard messaging app on your phone is called ‘Messaging’.  Signal has likely also been installed.  You can use Messaging right away to send messages to any of your contacts.  If you would prefer to use Signal you will need to log in to the Signal app with your phone number.  Additional messaging apps are available on F-Droid for download.
    
5. Browsers – A few browsers are available on your phone including the standard one (Browser) as well as DuckDuckGo, Firefox and perhaps Brave.  If you prefer others you can find them via F-Droid.

Other and Advanced

1. WARNING – In order to further maximize your privacy you should refrain from logging into any Google accounts on your phone (eg. The Playstore or any Google-related apps).  If you have a Gmail account it is best to access that from a separate computer.
    
2. Adding More Apps – The best place to look for additional apps for your phone is the F-Droid store (which is installed and ready for you to use).  All apps on F-Droid are ‘open-source’ and well-checked for any problems.  The Aurora Store (available at F-Droid and likely already installed on your phone) is a second option for finding new apps.  The Aurora store actually acts as a ‘middle man’ to retrieve apps on your behalf from the Google Playstore without you having to log in (always use the anonymous option on the Aurora app).  But, be careful not to download and then log in to any Google-related programs.  There is also an abundance of Android APK files (apps) that can be downloaded via your browser from apkpure.com and then installed to your phone.