Create a team where each class is represented, or one where all the classes are from the same planet to get a +5 team rating bonus. Do not spend all your coins on Bronze pack cards, because they are generally not worth it. Only use your bucks for the Gold Pack.
Bucks
Tap the "Offers" button to earn bucks for watching advertising videos or completing offers. Connect to Facebook to earn free bucks. Every consecutive day you log in will result in rewards, including free bucks.
Coins and bucks
Complete the achievements to earn more coins. Sell unwanted cards, such as soldiers with poor stats, for 10 coins.
Gear
When changing soldiers, unequip any gear that they hvae slotted for use on your new soldiers.
Perk cards
Perk cards are those that go in the right side slots of your soldiers. Unlike the gear cards on the left side which can be unequipped, the perk cards once used will remain in place. Do not use too many perk cards on your starting soldiers, because they will be replaced with better ones. The Gold card soldiers are more permanent and can be equipped as desired.
Soldiers
Each soldier class has a specific task. Some perform better when out of the mission area, while others will give an advantage when they rush in. You must have a balance between each class for the current task. Heavy Gunners and Demolishers are the two classes that rarely get into the mission area and are very useful.
Tactics
Equip three tactics, especially when in a campaign you need to rank well in. Equip complementary tactics if available, instead on focusing on the same type of improvement. You can get better tactical cards from better decks.