The Price's Write features tips I have run across or discovered myself through my years of writing and teaching writing. They are offered as suggestions to help you become a better writer. Our explanations will be brief, but I think if you follow these tips you can improve your writing. And more importantly, your audience will notice that improvement.They say "an" always goes before nouns starting with a vowel and "a" always goes before nous starting with a consonant.
However, this a-or-an rule should be governed by sound, not spelling.
For example, an hour is easier to say and therefore should be written not a hour. The converse holds true for words like united. A united team sounds much better an united team.
So let your ear be your editor when using a and an. If it sounds clunky, change it up.