Never click on a link that supposedly leads you to your bank. The link may look like your bank's uRL but in reality it may be a fake site set up to capture your banking details and steal your money. Always look at the uRL listed on the browser and make sure that it is the correct web address. It pays to memorise your bank's web address and to type in your online bank's web address manually every time.
Most online banking systems have layers of security measures. These include two step logins that involve pictures or phrases you have selected previously being shown on the screen before you type your password. Make sure every single time that the picture and or phrase is correct.