At lower levels when you do not have the Barrage unlocked, you can trigger spread-out Mines using Heavies because using solely Artillery will not destroy the Mines efficiently. This will prevent you from losing groups of Riflemen and Zookas to Mines.
At lower levels, placing Mines in a spread-out fashion, surrounding the base at least 3 tiles out from the first buildings, is the most effective way to position them and to stop troops from navigating around them.
Players might use their Gunboat's Artillery, Barrage, and/or Critters to destroy Mines before sending out their troops, so it's important to keep Mines separate from each other so attackers cannot clear all of them too easily.
Make it hard to avoid most of your Mines on the way to the Headquarters since Mines are an important defense against Warrior attacks.
Try to place your Mines so that they are not too close to your buildings. Attackers try to hit the Mines that are close to defenses while using the Artillery or a Barrage. If you place your mines further out, the Artillery or Barrage should not hit both the building and the mines.
It is best to avoid placing all or most of your mines on the shore where troops will be dropped off. A person can easily drop Artillery or a Barrage and clear a path and then use a Flare to help guide the Troops through the hole.
Mines do not visually change when upgraded; the only difference is increased damage.