First, you may not know a very interesting fact about your Gmail email address : you can use your regular email address as firstname.lastname@example.org and also email@example.com.
Second, it is possible to append a plus sign (“+”) followed by any text to your Gmail user name and hence create as many email addresses as you want (e.g. firstname.lastname@example.org redirects to email@example.com). However, many websites do not allow the usage of the plus sign in your email address and this trick is easily recognized by email spammers.
A better solution is to remember that full stops (“.”) are not considered by Gmail (e.g. firstname.lastname@example.org redirects to email@example.com as well as firstname.lastname@example.org), so you can use them to properly filter incoming emails (e.g. use email@example.com when registering to websites and then filter those messages).