WarFriends

It's really great to use rushers, a unit which rushes in for a quick attack, at the start of the battle as it can catch your opponent off guard.

Connect to Facebook when the game asks you to, it won't post anything on your timeline but you'll get some great rewards like the 24 hours VIP status and Premium currency.

Join a squad, they are similar to alliances in various base building mobile games, and you'll get a lot of info like stats, but you'll also be awarded premium currency.

Shot the boxes you see land on the battlefield as they offer various kinds of bonuses.

Watching video ads will give you extra money in the game so it's a great option if you hit a little bit of a block and need upgrades to improve your game.

Missions in WarFriends are done really great, unlike in majority of mobile games, so not only will you get additional cash by playing them but you'll also have a lot of fun.