Board Thread:Off Topic/@comment-14027812-20130914212156/@comment-24489208-20130914212741

Do what your heart feels is right. The main rule has to do with whether the first letter of the word is a vowel or consonant, but, English is a complete bitch of a language which breaks its own rules every 5 seconds. For an awfully long-winded explanation:

http://www.ecenglish.com/learnenglish/when-use-a