In my opinion your cannot make something "go viral" organically. It is something that happens naturally and with a great marketing campaign. There are more than 1.5 million apps on iTunes and the chances of your getting found are minimal. You need to create a marketing campaign that uses paid traffic from Facebook to spread brand awareness and increase app downloads. I would like to ask how your Facebook page has 24,000 likes, but your app only has 300 downloads? If did not pay for this "likes" then there is a way where you can turn those fans into app downloads.

Blake makes great points about going viral. That is not something that is planned, but you can do several things in order to give you app a chance for this type of exposure. Since most of those 24,000 people that like your FB page do not see your posts (because that's how FB works), I would start there. Promote you posts through FB ads to reach that audience first. They have already showed an interest in your product. You can spend as little or as much as your budget allows. Driving app downloads through FB can be a challenge, considering paying .50 a download can be difficult to stomach for a free app. But to get started and get some traction, it could be the best route.

After leveraging those you already have interested, you can look at other avenues (twitter, instagram, etc). I would also consider Product Hunt. A site I created recently was featured on Product Hunt after being hunted by a top influencer on the platform. Be sure to research Product Hunt thoroughly, though. It does you little good if you aren't featured and there is a process to follow for a chance at that.

Make some animated gifs and mini video campaign that you can put online and promote on twitter.

There are a number of things you can do to increase your downloads -

First there is the generic things, like stand out icon for the app store, and feature rich description (its important to note apps are like websites seo is important to get people to find your app), make sure you have a working app - check error reports and fix them - your app must be built in a way that users should have no reason to delete it.

It sounds like you already have a popular website with strong traffic, your main goal should be to convert that traffic into app users. Either through advertising the app via your website, or you can even use one of those plugins that detect if the user if looking at your site via their mobile phone, and automatically suggesting they use the app instead.

There are literally hundreds of thousands apps out there now, so to make yours get the users and keep them you have to work hard to keep the users you get - if you acquire 500 users in a month but lose 300, its going to take a very long time - use analytics to see exactly where you are losing customers and fix it, ever user is important.

Hi there, you mentioned that your FB has 24000 likes, I would highly recommend you take advantage of it. You can hold activities to attract users to download your app.

You can also tell your followers to complete a certain task, for example, invite friends to download your app. Rewarding the one who bring the most downloads publically each day.

Besides, you should also increase your app ranking on the app stores, because over 65% users discover new apps by browsing or searching on the app stores, and most of them just browsing the top 10 apps. You can increase your app ranking with the following methods:
· Optimize your app keywords -When you’re selecting a keyword, you need to take keyword relevance, traffic, and competition into account.
· Optimize your app title - It should include the keywords, which can increase your app ranking by 10.3%.
· Optimize your app description -Add 8~12 keywords in it（Google Play Store).
· Get app installs - which can boost app ranking in hours, highly recommend.ASOTOP1(http://www.asotop1.com/?from=cr-chris) provides this service.

Besides, you should also get positive app reviews(http://www.reviewapp4u.com/?from=cr-chris), because most people wil check the app reviews before downloading it, and iews from your former or existing users and choose your app. What’s more, data shows that 80% users have changed their minds about downloading an app based solely on the negative reviews they read.

Hope these methods are useful to u.