If you want to ge get free press coverage, one of the best way is applying for adwards. Participating in app awards is the most recommended channel and I would highly suggest you take advantage of it. It can give you tons of press, exposure, reviews and plenty of downloads. There are many app awards sites, such as Appy Awards, Best App Ever Awards, AppCircus competition, Apple Design Awards, Appsters Awards,etc. If you win, the prizes can be lucrative and a great career boost, most of the relevant new medias will report your app.
About getting featured on Mashable or some other app review sites, many of these sites are looking for apps such as:
When you apply for getting featured, you will most likely have to provide support material for your app. This is usually done in the form of a document containing the following items:
Before you apply for these awards, you'd better get positive app reviews to increase the downloads, because over 95% users will take the app reviews as one of the most important reference factors to judge the app, and most people prefer to download an app which has much more positive reviews.
Hope these methods are useful to you.
If your app is covering pain point and it really solves an existing problem and you are still working on it. Then don't do anything your app will be on someone's blog or in journal.