Ask HN: Tips and Tricks for beginners to promote your Android app?

Hey,<p>I've recently created a few Android apps to learn Spanish and French. The app basically has a long list of words, it dictates you a word in english, and then says it in Spanish. When I wanted to learn Spanish, I found that this technique was really helpful to quickly learn vocabulary, and works while I'm commuting, which saves a lot of time.<p>Now this app is pretty original, and is very simple to use, but as there is tons of language learning apps in the Android market, my app is always listed like 20-30th in the list when searching. I would like to know if there is an easy way to promote my apps. I've previously tried to promote some apps on Facebook by paying 30$, but it never compensated for the price gained afterwards. I've created some free versions so that people can try it out, but still not a lot of purchases.<p>I would like to know if someone has managed to successfully market their apps, without paying 1000$ out of the pocket ? I'm not looking to make a salary with these apps, but at least compensating me for the time I spend programming them :).<p>Thank you for any help. I'm sure this topic will help other people discover some tricks!<p>Here are my apps if someone is interested:<p>Spanish: Free: https://market.android.com/details?id=com.pervychine.learn_spanish_lite Paid: https://market.android.com/details?id=com.pervychine.spanishincar<p>French: Free: https://market.android.com/details?id=com.pervychine.learn_french_lite Paid: https://market.android.com/details?id=com.pervychine.learn_french