Orders
The easiest way to progress in Soldiers Inc. Mobile Warefare is by following the orders the game keeps throwing at you in the top left corner.
Busy
Make sure you keep busy by always working on something and only use your boosts when absolutely necessary.
Red Target
Keep an eye on the red target sign that is underneath the mission you are on as it indicates potential raids where the bonuses they give will benefit you. These missions can usually be easily acomplished by pressing the 'Send Strongest Squad' button.
Rewards
Whenever you complete a mission you will earn a reward. There is no need to immediately claim it, check your current supplies to make sure you haven't hit the cap for it before you claim it otherwise it will be wasted.
Extra Construction Slot
Take advantage of the extra construction slot that allows you to build two Buildings at once when you when you reach level 5 as it is a temporary bonus that disappears after three days.
Join a Combine as soon as possible as doing so will make a huge difference to your survival odds when you reach the later stages.
Daily Bonus
Make sure you log in regularly so you gain the daily bonus that is available each day and also acquire shipments which offer smaller bonuses.
Boost Annex
Build the Boost Annex first as this building will boost your Resources substantially.