We spoke previously on the importance of early-stage marketing, but you don't have a huge audience built yet... and even if you did, you're not sure what to do with it. What is there to tell them? Your app isn't out yet, so they're really just stuck waiting.
Your pre-release audience is a key asset, and getting them involved with your product before release can mean the difference between a deleted email and a download. Here's information on how you can use this email list and audience you've built through every stage of your app development.
Having a small audience built before you've even begun designing the app is a great position to be in. Your audience can tell you what's good and not good about your app idea before the real stages of investment have hit, saving you tons of time and money of mistakes.
Send an email to your email list to tell them more about your idea, and ask these questions of your email subscribers. Make it a real discussion between you and your subscribers about your idea.
In order to get more exposure and more meaningful feedback, download the free marketing directory on this website and post on some of the forums listed on it (like Reddit) with what you emailed your list. Interested members will join your email list, making them part of the community.
This time (as well as anytime) is a great time to provide a survey and ask people for their eMails at the bottom of the survey. You can ask demographics and situation questions in order to collect meaningful data - here's an example of a good survey at this stage. You can use SurveyMonkey or Google Drive to run your survey for free.
This is where you can talk to your audience about your prototypes and design, and get their feedback on whether or not they'd use it. Ask for critique or feedback on both graphic design and UX (but keep in mind that your audience is not in those professions). If you have a shareable prototype made with AppCooker or another program, share it with your email subscribers now.
The procedure here is similar to above; find the people on the internet that do graphic design and enjoy app design on forums, and reach out to them. Search 'design' or 'critique' on Reddit, and select a couple of good subreddits to post in.
If you've already sketched out the screens of your app (which you should have by now) on paper, you can use an app like PopApp to make a working prototype, which you can then share with beta-testing websites listed on the marketing directory.
If you have graphic design of your app completed or nearly completed, you can post it to Behance or other art websites as well. (However, do not post to DeviantArt - in their user contract is a clause that you forfeit the rights of your artwork to them, and that will be a legal nightmare when it comes time to release your app).
Development is a great chance to get people enrolled in your idea via beta-testing. Send an email out with an invitation link to a beta-testing service, so when you're ready to send a beta out everyone else is already signed up to the beta-tes
This is your best chance to get on the beta-testing websites in the marketing directory as well, to attract an even bigger audience to your apps' email list. This can translate to much more downloads when you finally hit the app market.
Again, post on forums and Reddit. When asking for feedback, make sure it is feedback from actual developers. They often have cool libraries and code sets they will recommend you use in your app to add extra polish.
Simply googling a programming challenge you or your programmer experience can lead you to really great, free codebases. And every time someone is helping you with a program problem, they stop by your website - which is another chance for you to get the word out and collect email addresses
If you've kept your audience engaged through all the stages of your app development, they'll be quick to buy your app when it comes out - not to mention all the great feedback and guidance you'll have gotten in developing your app.
Keeping an audience engaged also means constant growth of your email list as you work on your app, meaning more downloads when it is finally time for the release of your app.
And if they don't download now, then they were never a fit for your app anyways.