Base
Work on establishing your base first before you start attacking other players. You will have plenty of opportunities to raid other players loot later in the game.
Mines
A good tactic is to place mines across areas where your enemies have to cross and then lure them there.
Outside Zombies
Don't forget to tap on the zombies that are wandering around outside your base as they can hold anything from extra bits of salvage to premium currency.
Survivors
To give yourself the best chance of surviving the zombie Apocalypse you should only ask survivors who have useful skills to join your squad. You can do this by checking their score chart and skills record.
Special Skills
Remember to take advantage of your survivors special skills as they can make a big difference in battle.
Supplies
Make sure you regularly stock up on your supplies and other necessities like gas and pile them close to a tower so you makes it more difficult for the enemy to take them away.
Events
Consider attempting the Events whenever they are on offer as you can earn some easy free Bloodstones along with plenty of experience and bonuses.
Upgrade
Upgrade everything the first opportunity you get because when you level up you unlock new buildings and sometimes new update options. Make upgrading your defensive towers so you can protect your loot better your first priority. Then work on upgrading your survivors and then everything else.