It's not uncommon to have tens or hundreds of online accounts, so it's increasingly important to be sure that they're all safe. Your Gmail account might be at the center of your online identity, so it might be better to take extra steps to make it safer..
The best way to make your Gmail account safer against malicious access attempts is to enable 2-Step Verification (sometimes referred to as 2FA, for Two-Factor Authentication). It might sound a bit scary if you've never heard about it, but it's actually easy to set up and will make a huge difference.
2-Step Verification will add an additional step to login to your account, that only you will be able to perform from your phone.
Scroll down until you see 2-Step Verification, and click on it.
Now you can just follow the guided procedure to set up this secure authentication. You will be asked to input your password again and then set up your phone.
After you're done, you'll be presented with a few options to authenticate your account. We personally like using the Authenticator app. It will present you with a QR Code that you can scan with a third party authentication app like the very good Authy to authorize logins to your account.
You can even scan it with 1Password, which we recommended before, but it's not good practice the keep your password and your two-factor token in the same place.
Other security tips
Generate and store a strong password. We recommend 1password.