Always update to the latest version of iOS to benefit from the latest security patches and improvements. 

Set a strong passcode that is not easily guessable. Avoid simple sequences or commonly used numbers. Consider using a six-digit passcode or even alphanumeric for enhanced security. 

Use biometric options such as Face ID or Touch ID for a secure and convenient way to unlock your device, authenticate downloads, and Apple Pay transactions. 

Activate ‘Find My iPhone’ in your iCloud settings. This feature helps you locate your device if it's lost or stolen, and allows you to remotely lock or erase it. 

Set up two-factor authentication for your Apple ID to add an extra layer of security, especially for iCloud and Apple Store transactions. 

When creating new accounts online, consider using the Sign in with Apple option when given the opportunity to do so. This option allows you to use a randomly generated email address for your account instead of your real email address, and makes it much simpler to audit where you have accounts online (Settings > [Your name] > Password & Security > Apps Using Apple ID). 

Ad tracking across apps should be disabled by default, but it’s good to double-check and confirm that you didn’t enable it inadvertently at some point.  

To disable ad tracking;

Open Settings > Privacy & Security > Tracking and make sure Allow Apps to Request to Track is disabled. 

Scroll to the bottom of the page at Settings > Privacy & Security > Apple Advertising and toggle Personalized Ads off. This will opt you out of interest-based ads in Apple apps. 

Go to Settings > Privacy and review permissions for each app. Limit location access and ensure that apps only have access to data they need for functioning. 

Scroll to the bottom of the page at Settings > Privacy & Security > Apple Advertising and toggle Personalized Ads off. This will opt you out of interest-based ads in Apple apps. 

Disable access to features like Siri, Control Center, Notification Center, and Wallet from the lock screen. Go to Settings > Face ID & Passcode (or Touch ID & Passcode) to adjust these settings. 

Utilize a reputable VPN service when connecting to public Wi-Fi networks to encrypt your data and protect your internet activity from snooping.
 

Ensure your data is regularly backed up to iCloud or your computer. This helps to secure your data and facilitates easy recovery in case of device loss or damage. 

Avoid jailbreaking your iPhone. Jailbreaking can expose your device to security vulnerabilities, potentially compromise your personal data, and void warranties. 

Periodically check what permissions apps have on your iPhone. Adjust permissions to minimize access to essential data like contacts, camera, microphone, and your location. 

Turn on automatic app updates to ensure that all your apps are up-to-date with the latest security patches. Go to Settings > App Store > App Updates. 

Avoid connecting to unsecured public Wi-Fi networks. If necessary, ensure you are using a VPN to protect your online activities. 

Be vigilant about phishing attempts via email, messages, or suspicious websites. Do not click on links or download attachments from unknown or unsolicited sources.