Making Money with Android

Best Makreting strategy for launching a big product

Hello guys ,
we have been developing a product about a mobile social network for months and the launch date is pretty soon
we did the following steps so far .
1-created a landing page for the product for users to subscribe for newsletters and we gonna send emails once we release the product .
2-created facebook page and made alot of ads but unfortunately the result was not very promising because the product has not been launched yet .

Our target is 100k installs in the first month we already have most of the money in the development so we have only 1 shot left so we would like to know what are your suggestions about Marketing strategies that we should follow with the minmum cost.

thanks ,