Why not take <u>a</u> trip to Lake Lagano. It's such <u>an</u> interesing place to visit at this time of year. Also, you'll find cheap accommodation.
One should use "a" when the following word begins witg a consonant. One should only use "an" when the following word begins with a vowel. You should not use either if the following word is a proper noun. You should also not use either if the following noun doesn't refer to a single thing(the following noun may be singular...but this doesn't always means it refers to a single thing)
