If you are asked to log in somewhere, do not click on the link in the e-mail. It is that simple. If it's about banking, go to your bank's website and check the message service there. If it's about your documents online from a cloud service, go to your own login page that you know and log in there. If it's about a service from a customer, you can call them to confirm. Never log in with your own data, but only with the data they have provided. This prevents you from clicking on wrong links, accepting wrong proposals or downloading programs or giving permission that is malicious or illegal. It ensures that you are smart.