Hints:

Stage Select:
     On  the Title screen -where players see "Press Start" - enter the
following  code  using  the  Control  Pad: B, A, R, R, A, C-Right, Up,
Down,  A.  There  will not be any indication that the code has worked.
Select "Replay Mission" from the main menu, then press the L Button to
display  all  of the missions (the R button chooses which side you are
playing).

Zoom:
     Hold L press C-Up or C-Down to zooom in and out of the battlefield.

Economics:
     Build  a Tiberium Refinery. Sell the actual refinery and you will
receive  $1,000  credits.  You end up with an ore truck. You save $200
credits.  If you were to build and ore truck through a war factory, it
would cost $1,200 credits

Sell Men:
     Place  your Mini-Gunners really close to a sand bag wall and sell
the  wall. If your men were close enough, and it works right, your men
have been sold.

Sandbagging trick:
     Use sandbags to build all the way to your enemies base. Now build
some defenses, guns or whatever to take them out! A ton of turrents is
especcially effective!

Sell vehicles:
     Place  a  not  wanted  vehicle  on  a repair bay and put the sell
cursor over the vehicle and preess "A".

Be able To Build Opponent's Units:
     Get  your  engineer  to take over a enemies construction yard and
you can build their units

Sandbag trick:
     Build  sandbags  around your base with one gap and the enemy will
only  atack  through  the  route  as  the AI doesn't recognise it as a
target.

Hidden UFO:
     While  playing  as the Global Defense Initiative (GDI) on mission
6,  gain  access  to  the  Air  Attack. Then order your bombers to fly
toward  the  lower  left-hand  corner  of  the  screen  and  destroy a
designated  target.  Follow  the planes. As their bombs plummet to the
ground, you should see a UFO hovering in the cleared area!

Steal Enemy Harvesters:
     You  can  steal  the  enemy's harvester by capturing the refinery
while  the  harvester is depositing money into it. This comes in handy
on earlier missions when you cannot build more harvesters.

Economics:
     Need  an  Orca but don't have enough money? Instead of buying it,
simply  build  another heli-pad... and then scrap it. You will be able
to keep the Orca that came with it and save 450 credits!

APC Trick:
     If  you're  playing  as  GDI,  and  you  have  access to APCs and
Engineers,  then  you  can  try this trick. Build 2 APCs, and put them
each to a C-button. Now build 10 engineers, split hem into 2 groups of
5, put each group on a C-button, and load each group onto an APC. Now,
drive  the  APCs over to the enemy base, and park them next to the NOD
construction  yard/barracks/airstrip.  If  the APCs are blown up, it's
okay,  the engineers will walk out still alive. Send all the engineers
into  NOD  buildings,  going  into  the  construction yard first. Now,
whenever you blow up a NOD building, they won't be able to replace it.
And, if you captured their Hand of Nod or airstrip, then they won't be
able to build any more units if you blow them all up.

Easier building:
     Highlight  a  unit  to be created from the toolbar, then press A.
Hold  Z  and press A after receiving the "Unit Ready" or "Construction
Complete"  message  to  build the same unit again without returning to
the toolbar.

Finding money:
     Destroy the churches in the villages to find $1000.

Build NOD attack chopper:
     To  build  an  attack  chopper for the Brotherhood of NOD, simply
take  over  their  main base and the option for an attack chopper will
become available.

Faster Ion Cannon and Nuclear Weapon charge:
     Build  more  power  plants to get a faster Ion Cannon and Nuclear
weapon charge.

Taking out Lasers:
     The  fastest  and  easiest way to take out Lasers is to use three
flame tanks -- you will barely get damaged.

Taking out Guard Towers and Advanced Guard Towers:
     Build  Artillery  and  send them to attack those structures. They
shoot from such a long distance that the Towers can not shoot back.

Tiberium Factories:
     When  you destroy all your opponent's Tiberium Factories, you can
shoot  one  of  their structures a few times for them will sell to it.
However, make sure you take out their main base first or they will not
be able to rebuild the Tiberium Factories.

Keep tanks from getting destroyed:
     Get  some  men  and  put them in the front of your tank. When the
enemy opens fire, they will shoot at the men instead of the tank.

Enemy shoot each other:
     Take  a  quick  unit  and speed it through two enemy units to get
them to shoot each other.

Distracting the enemy:
     You  can use units such as mini-gunners to distract the enemy and
overwhelm them. They will not attack until the gunner dies.

Run the enemy out of money:
     First  find  the  enemy  base, then find all the ways in and out.
Once  you've done this build sandbags all the way up to the enemy base
and  block  off the entrance (be carefull that you don't get too close
to the entrance you've just blocked off or the enemy will shoot a hole
in  your  barrier).  The  enemy  harvestors can't get in to get to the
refineries and they can't get out to harvest, therefore the enemy runs
out  of  money and it is a lot easier to destroy their base. The AI is
too dumb to do anything about this.