The easiest way to promote on a shoestring budget is guest posts. Write about the problem your app solves on sites where your target customers will read them.

Make sure you've got a strong marketing funnel for the people who click through your articles — if you're not capturing leads properly (and converting them) all your marketing efforts are wasted.

I've worked with a lot of new businesses and helped them bootstrap to success using this approach. It works as long as you stay consistent and *truly* help your reader in the articles (trust is huge).

I'd be happy to review your strategy and help you adjust it for maximum exposure (and potentially adjusting your inbound funnels). Let me know if you'd like to set up a time.

Good luck!