Never share a foxhole with anyone braver than you. If your attack is going really well, it's an ambush. The enemy diversion you are ignoring is the main attack. The easy way is always mined. When you have secured an area, don't forget to tell the enemy.
Teamwork is essential.
It gives the enemy other' to shoot at. Make it too tough for the enemy to get in, and you can't get out. The only terrain that is truly controlled is the terrain upon which you're standing. The easy way generally gets you killed. If you take more than your fair share of objectives, you will have more than your fair share objectives to take.