You can store form elements value in preferences with less efforts (as compare to version below Liferay 6.1).
You just need to follow few syntax to achieve this functionality. Lets go step by step.
Define your AUI element with below syntax
<aui:input name="preferences--showFeedTitle--" type="checkbox" value="<%= showFeedTitle %>" />
It should follow pattern like preferences--paramName-- .
And make sure you use below Configuration class in your liferay-portlet.xml
By using this way we dont need to write any code to store form element value into preferences . DefaultConfigurationAction class will detect form element with specified syntax and store the same in preference for you.
In case if you want to retrieve value from preference then directly use
// No need to use that syntax to get value
You can also visit Liferay for same thing . Following is my community blog link. Unique way to save portlet preferences