Keep your dates flexible. Many airlines have specific requirements for a minimum and maximum total number of days to be spent in a location in order to get the best deal. For the cheapest flights, stay for a minimum of 2 nights and a maximum of 30. Try to stay at your destination over a weekend, as flights that bookend a Saturday night are cheaper than those that lack a Saturday stay.
In Google Chrome or Safari, incognito is enabled by hitting Command (or “Control” if using PC), Shift, “N”. For Mozilla Firefox or Internet Explorer, hit Command (or “Control” if using a PC), Shift, “P”. This will open a new browser window where your information is not tracked, thus not inflating prices as you search. Note: if you're using an older version of OS X, open Safari then click “Safari” in the menu bar, and select “Private Browsing”.