Tips'n'Tricks
  
  Here are some tips which you can use to surprise your enemies:  
 
General Tips
Here's how You can use civilian vehicles in Tiberian Sun:
Take a Mutant Hijacker in to a city and find a Car, truck or a bus, and select it. Now you have control over the Vehicle. They are used as transports.
The first thing when starting a game should be to take care of money income. Build two or more rafineries and start harvesting that tiberium as fast as possible.
When you are starting a game don't forget about defence of your base, but try to balance this with the need to explore as much of the map as possible. It is very important to find your opponents base as quickly as possible.
Use CTRL+(F9 to F12) to memorize the possitions of your opponents base and more important buildings. If he is NOD he will quickly try to cloak them but you'll have their possitions memorized.
When your opponent finds your base move your MCV to another place to confuse him. Provided that option was enabled in starting the game.
GDI Tips

When attacking your opponent with an APC use this tip. Send in the APC with a Ghoststalker and 4 Engineers. If your opponent tries to kill ghoststalker engineers will capture some buildings. If he tries to kill engineers then the ghoststalker can destroy some buildings. Eitherway, you will do a lot of damage.

If you need a good defense system early in the game, disc throwers are a good option. They work well against things that are not powerful. Build some light infantry units and mix them with the disc throwers, so when being attacked the disc throwers will not all blow up at once.
A unit to use as a base defender is the Hover Multi-Launch Rocket System (MLRS). The Hover MLRS can attack air units and quickly destroy tanks. Adding Wolverines will make your base defenses even stronger.
The most expensive thing you can destroy with an Ion Cannon is a Helipad with a helicopter sitting on top of it.
This tip is for people who don't mind sacrifacing some units. Send some infantry to a Tiberian field near the enemy's base and keep them moving in the Tiberium (make a looping waypoint). When your infantry are converted into Visceroids, watch them go into the enemy's base and take them out. For this tactic to work, at least 3-5 adult visceroids must reach the enemy's base.
Try to build concrete arround your main buildings. This will prevent your NOD opponent to sneak underground units in to your base.
Another thing when fighting NOD opponent. Build Mobile Sensor Array (MSA) as quickly as possible and deploy it to cover your base. Again this is to prevent underground units reaching your base undetected.
NOD Tips
At the beginning of the game send a fast unit to scout the other persons base. Mark out main buildings if they are NOD so you know where they are when they stealth.
Use a Subterrainium APC with a Mutant Hijacker to emerge near the enemy's Mammoth Tank, using this unit to destroy the enemy's base from within.
Put Stealth Tanks around your major buildings or units to create a surprise defense.
The Artillery Units are one of the best defense's nod can have. They can attack the enemy units from a great distance, enabling you to know when the enemy is coming with out seeing them on your screen.
Always try to stealth before the enemy can see your base, to do this scout a large area around your base and set several groups of infantry in guard mode a screens width away from your construction yard.
Try to build concrete arround your main buildings. This will prevent your NOD opponent to sneak underground units in to your base.
As much as possible use underground APC to surprise your enemy. In the APC put Cyborg Commando and 4 engineers. This is the most leathal combination as Cyborg Commando is very tough to kill.
Here are some cheats
Well, they are not exactly cheats. Let's call them shortcuts...
If you want to kill a Cyborg Commando, with out losing all of your units, there is a very simple way to do it.(You have to be able to build a GDI Firestorm Wall Generator, and Firestorm wall sections.) First fortify your base and build it up until you have the option to build a Firestorm wall, and sections, then build firestorm walls across any sections where an enemy can get into your base. When a Cyborg Commando is over one of the sections turn the Firestorm generator on and all of your problems are solved.
You can try to steal your GDI opponent's Mamoth tank using mutant hijacker. If you manage to do that in his base he will have to suffer a lot of dammage.