First you recon the enemy position carefully. Choose a weak spot from the defence. Concentrate the supporting infantry arms to that area and use artillery and mortars to soften the enemy,if you dont have any, use the infantry supporting weapons for direct support. Smoke the area and penetrate the defence from a narrow area. One good option is to attack during the night, because of the worse LOS for the enemy, but that will ofcourse effect your men also. Once you are in the enemy defence zone, you will use fire and movement, in order not to give time to the enemy to move reinforcements to the area or for him to retreat. Important thing is not to stop or loose enemy contact. Then you just push until the area is cleared. Important thing is to get close and fast, Once you are inside the enemy defence zone you have better odds. If you have to move long distances in open space before getting on the enemys skin, your chances of success are lot worse. So basicly move close concealed, concentrate fire to penetrate the enemy position, use fire and rapid movement to put your enemy in disorder and take his position.