So, you want to give your app the best chance to stand out amongst the others right?
Well, for that, it is very important to notice how to format your description to make it easy for customers to read it, and to get your app approved.
Without further ado, let me give you some points worthy of notice:
1. Pay attention to grammar and punctuation. This has a big impact on the perception of your app's quality and polish. There may be the odd case where 'bad grammar on porpoise' is part of your schtick and how you captivate the audience, but outside of that, keeping language closer to formal is a Good Thing™.
2. Ask yourself basic questions like: "What do people get from downloading your app? What is your proposition of value? ". Answer those questions as succinctly as possible.
3. Use simple, accessible language. Making your description easy to understand will increase your chances, as more people will understand what it's all about.
4. Structure your description from most important to least important stuff (even if you think everything is important!). Explain your app in one sentence. You can then expand with one paragraph - less than 300 characters. You may want to talk more about your app, but the customer may stop reading right here. You can then expand with 2 or 3 extra paragraphs, keeping it below 1500 characters. Finally, if you feel you still have more to say, of course, you can, just be aware the customer may not read the trailing part.
Note: the 300 and 1500-character points are important, because some platforms may limit the answer to those lengths. It's OK to provide longer descriptions, but we may have to shorten them depending on the platform.
What NOT TO DO:
I have already told you some do's, now it is time for some don'ts:
1. Don't self-rank your app. Sentences like "#1 app in the app store!" will be rejected by the app stores from the get-go. Superlative words that put your app as if it is better than everything else are also no good: "best xyz app in the world!" is also a no-go.
2. No profanity. Even if your content and audience are geared toward an adult audience, the app store is not age-restricted. Although not prohibited, innuendo may not be the best choice either.
3. cryptic bullet lists of single words (or too terse). While it's OK to provide lists if you want to, try to be more descriptive t make users excited about your content.
4. Hyperbole and excessive punctuation. While your content may be the most awesome! OMG!!!!ONE!!!1!!!, this kind of description makes for a poor presentation.
Also, avoid adding testimonials as part of your App Description as it might make it harder to approve your app in the App Store.
If you follow these guidelines, you will be on the right track for writing a great description for your app!