Skills in this doctrine revolve around making infantry more valuable in combat. This comes in handy in missions, where the majority of your army are infantry. In missions where infantry makes up a half of your army, you can pick this doctrine, if you are good ad commanding infantry, the terrain provides many covers or when defeating the enemy is easier than with vehicles (e.g. vehicles have little ammo and fuel throughout the majority of the mission).
Each faction has Hand grenades, Piggybacking, Infantry drills (Germans; more accurate fire) or Take Cover! (Soviet; slightly reduced damage in some types of terrain). Alliance, on the other hand, has First Aid instead of Piggybacking, and Extra magazines (extra 20% of ammo). Each of the factions can quickly unlock Hatch Lookout, which is useful, but it is better to reveal terrain by sending out infantry. First aid, on the other hand, is highly useful, especially for novices. You can heal any severely wounded soldier without a medic. Each infantryman receives this skill for single use, even crews of vehicles. This skill is very useful, if you have lost many of your infantrymen away from your medics, or the last of your medics has died. Heal your men after you have cleared the battlefield of enemy units, or after the battle. Otherwise, your men will get fired at.
Smoke grenades and Grenade drill are a perfect combination, if you want to rely on grenades in combat. Smoke screen may be useful if there is nothing but open terrain between you and the enemy, and you want to sneak past. Also, it works excellently for covering your units, while retreating. The enemy loses sight of your soldiers and becomes unable to shoot at them.
demolition kits and Backpack allow your men to take more gear into the mission. This way, they will be capable of dealing with large infantry units, and even tanks. AT grenades are very effective, because they often affect the upper part of the vehicle, where armoring is thinner. Sprint increases movement speed of your men, whereas Tough guy affects the survivability of your men (reduces damage taken). Binoculars becomes useful only in missions, where there are your officers and you have to destroy heavy fortifications with enemy infantry or cannons hidden. In the rest of the missions, you will not be using this skill too often.