Command and Conquer hints:
These hints and tips are for general game play and are not intended to get you through any one particular mission.
Don't neglect the engineer, a key unit in the game. It is often easier to capture a building than try to destroy one. Concentrate on stealing key buildings of the enemy (Construction yards, Airstrips, etc..)
Find out the strengths and weaknesses of the units in C&C and use each to it's advantage. NOD flame thrower tanks can easily wipe out troops and bikes, but are often overlooked. Regular guard towers are generally passed over for the more lethal Advanced guard towers, yet the Advanced towers can be very susceptible to Commando bombing. Continue to build regular guard towers to prevent infantry attacks.
Find the Achilles Heel of your enemy! NOD obelisks can be quite deadly, but without power they're completely useless. The same is true for Advanced Guard towers, Advanced Communication Centers and the Temple of NOD.
Create and use your air forces often! By creating several helicopters and then assigning a team key to them, you can instantly call strikes on harvesters and other units out in the field that don't have rocket capability. Remember, Orca helicopters work best against units, while Apache Helicopters are useful against infantry.
Spread your buildings out. In multiplayer games, a nuclear weapon can do heavy damage to a tightly formed base. By making space available, you can decrease your chances of losing due to an overwhelming nuclear attack.
Always guard your harvesters. They're basically the only source of income you have. If you're having trouble keeping them alive, place some tanks and other air defenses in the tiberium fields. By denying your enemy access to tiberium, you can slowly starve them into defeat.
Never sell your construction yard. If you're in need of funds this badly, you'll need to attempt some other type of desperate move like capturing an enemy building or begin searching for crates (in multiplayer games). Selling your construction yard is usually the final step before your defeat.
Use the special keyboard commands! Team functions, and guarding a specific unit or building can only be done by using the appropriate keyboard commands listed in the README file on your CD-ROM. These tactics are crucial if you're playing a seasoned veteran of Command & Conquer! (They're probably using them too!).
Don't overlook your infantry. A group of four or five rocket infantry can keep helicopters at bay, and a far cheaper and harder to hit. Also, groups of grenadiers can be highly effective against Obelisks and turrets, since these can only attack one man or vehicle at a time.