Ransomware:
Always check incoming email addresses. Although they may appear legit and from a friendly source, there may be a letter or digit or other which is not correct, eg 0 instead of O in the server address, and if unsure contact the sender by phone. If there are any attachments which need opening, don't open them until you can verify they are all legit. Make sure you back up your data and as suggested by Tim last night, your backups to be separated from your pc, eg external hard drive safely secured. Emails tend to be the easiest way criminals are getting access to your PCs and phone, by you clicking on links or opening emails, before checking.
Email account access on mobiles:
Your mobile is connected to various apps and the internet. Make sure you have 2-factor authentication (2FA) turned on in your email account. 2FA should be used on all other apps, as well. This will mean that if someone gains access to your personal info, such as ID and phone number, and tries to log on to your emails to create an account, you will be notified provided you have 2FA in place.
For emails go to settings and you can turn on 2FA from there. Other apps may vary.