10-4 mines work well on beaches, in fact, underwater is the best place for mines because they cannot be seen. Look for choke points on beaches or covered positions where enemies will be tempted to land their craft.
I've come to believe that having one or 2 guys mining clutch for defense on zones 1, 2, and 3 in Laguna.
Zone 1: The left by the docks, the right by that big rock, center in front of the shielded MG (just right of it).
Zone 2: In the river, on the far left road (that leads to the shack) and on the crest of the big hill on the right.
Zone 3: All over the river, on the bridge and (if possible) on the enemy's side of the broken bridge.
Also, hell yes to smoking turrets, though rocketing them is better (;