1. Build a microsite. This one or two-pager showcases your app to the web audience. Take cues from Snapchat and Path.
2. Build a teaser website. Do this a month or two before your launch to collect email addresses of people who would like to know when the app launches.
3. Start a blog. Attach it to your microsite. Write interesting content that will draw people to your website. Buffer app does this really effectively.
4. Share your content. Use your Twitter, Facebook, Google+ and LinkedIn profiles to promote the app several times in a week.
5. Create a product video. Make it creative, funny, thought-provoking or personal. Tell the story, but in a way people can identify with. Here's a great one as example from the Dollar Shave Club.
6. Get press, tons of it. Entrepreneur Neil Patel says: "Press is the best way to kick start your startup, and the best way to get it is to manually reach out to journalists."
7. Pitch to app review websites. Sites like 148apps, AppStoreApps and AppAdvice can generate a lot of buzz for your app if they mention it.
8. Contact bloggers who would care. Identify bloggers who write on niches that relate to your app. For instance, a children's app can be pitched to bloggers write write for mothers.
9. Apply for awards. Look into awards such as the Kiip Build Fund or The Mobileys. If you win, you also get a ton of press, not to mention winner's booty.
10. Start a podcast. Publish it on iTunes or your own website. Draw content from the niche your app caters to most.
11. Always be collecting emails. Gather potential customer emails through Facebook, Twitter or your website. An email list of people who have opted in is a powerful marketing tool.
12. Create a six-second how-to series. Make the most of Vine with videos potential customers will find useful. The hashtag #howto is one of the top trending tags on Vine.
13. Use Dubbler. Promote your blog posts or content having to do with your app's niche on Dubbler -- a 60-second audio social network.
14. Post on Pinterest. Use blog images, infographics and visual content from your app to create content on your Pinterest board. You can even use happy customer photos or hold contests.
15. Manually recruit customers. The creator behind Canvsly reaches out to local art schools, libraries and pediatricians to get more customers. Know your audience and find them.
16. Run a contest. For example, you can encourage people to tweet and share content on their social networks promoting your app. A random person every week can win a promo code to download your app for free if it is a paid one.
17. Create a Facebook group. Form a group for people with common interests related to your app's niche so they can meet and socialize regularly. If your app caters to hikers, for example, create a hiking group.
18. Get speaking opportunities. Research events that touch on the topic your app addresses and make an appearance. Start small and get recognized as an authority in the space.
19. Take advantage of voicemail. Include a creative mention of your app in your phone's voicemail recording.
20. Be obsessive about resolving negative reviews. Remember: A happy customer is a brand ambassador for your app.
21. Make good use of App Store Optimization. You can find it at the app store.
22. Contact admins of related Facebook pages. Look for pages with 100k+ likes and reach out to their admins. Make sure these pages have something to do with the focus of your app. Then give them a compelling reason to mention it.
23. Optimize your email signature. Provide a catchy one-liner about your app along with the link to download it in your email signature.
24. Consider offering a promotional price. If your app is a pay-to-download one, consider a promotional pricing of $0.99 during the launch time. This price point encourages impulse purchases.
25. Integrate social within the app. This will make it obvious to users to share with others. Path app allows users to share photographs on social networks and Draw Something makes sure you rope in a friend or more...