Look around you. You might find quotes on calendars, magazine or even greeting cards. When you find a memorable quote cut it out and paste it into a scrapbook so that you won't lose it in a shuffle of papers, or make a note of it on your cellphone or computer to impress your Facebook friends later.
When you read, keep a quote journal next to you so that you can easily write down what resonates with you or how you felt when you read something.
There are lots of great quotes to be found online. If you are using a quote in a blog post, it's considered good etiquette to link back to the blog as a way of crediting it and thanking the author. Use a tagging or bookmark system so you don't lose track of your favorite ones.
Pick up autobiographies of your favorite people. When they tell their story in their own words, they may include nuggets of wisdom that might be perfect for a quote. Using these kind of quotes should surprise and impress people when they hear them.
Perk your ears up during celebrity interviews. Most of the time you will just hear inane banter of the rich and famous. However, every once in awhile a gem will slip through.