Everything in Navyfield has evolved over the years, except for bringing in new players. Aside from the uninspiring "Invite a Friend" system to hopefully bring in people who might want to play.
It's really not enough, though.
-Facebook Share competition
-Viral Marketing
-Ask the players for idea
But let's get something going.

The best incentive and at the same time best way to reduce low level attrition is comprehensive guides, especially for crew setups. And in no way should the incentive be freebees.

Bugfixes. That would be the best incentive. When the game crashes after your second battle you will lose itnerest veeeery quickly.

fixing the game will intice new and old players