General Team Strategy
In order to succeed at Ghost Recon 2, you will need to do more than just aim the crosshairs and fire. By giving your troops the proper commands, you will use strategy to complete each mission. There are general guidelines that can be helpful in this regard. For example, keep in mind that injuries your teammates sustain in one mission will carry over to the next one--they might need to "sit out" a mission or two. Also, in later missions things can get pretty intense and fast-paced, as you will have to control many support units. At this time, it's probably the best plan to send your troops someplace safe and secure. There won't be much for them to do, anyway.
Use Your Soldiers as Bait
This is often the fastest and easiest way to clear a board. Send your troops out in advance. While they are drawing fire, flank your distracted enemies and take them out.
Solo Mission Achievements
In order to rack up solo mission achievements, play the first turret sequence on solo mission mode (easy level). This is the easiest sequence in the game, and an almost guaranteed way to get three achievements in a row.
All-Secondary Objectives Achievement
This achievement is based on destroying fleeing vehicles on a level, often something that happens as a natural consequence of completing the board. However, two levels can be difficult. The first is "Who the hell are these guys?" In this mission, two vehicles are particularly difficult to find, but luckily they're right next to one another. At the checkpoint (after you get tank support), immediately turn right. Go up the ramp and destroy the two trucks.
The second mission is called, "You'll be inserted solo." To earn the achievement, you need to destroy three trucks. Just before you enter the graveyard you'll see the first two, dropping off enemies. Use the Zeus or grenade launcher to make quick work of them before they pull away. After you are granted the mule, you'll see the third truck, near the end of the mission.