There are quite a few defensive airsoft tactics. This one is on the theory kill or be killed. Instead of waiting in a position for an enemy to come by(which may not even happen) try going and finding your enemy. This will create confusion on the attacking team and will leave them retreating and or being laced up.
Step 2: Defensive tactic 2
I named this tactic Black Hawk. The defending team (depending on team size) will place 4-5 teamates in trees lining a path or commonly walked area, and send other teammates(preferably fast runners and maybe a fat kid) to lure the attacking team into the ambush area they will take positions under the trees that contain a "black hawk" remain hidden until majority of the attacking team is in the zone. The problem with this tactic is that if the attacking team sees the "black hawks" in the trees it could be very deadly for the defending team but if this is performed correctly it will result your team with another victory. Remember you have the element of surprise use this to your advantage.
Step 3: Sniping positions
Snipers can be verrryyyy deadly in airsoft. A snipers ideal location is always somewhere up high where he can see most of the playing area. Snipers should not be directly with the rest of the defensive positions but rather off behind and over to a side. One spotter should go with the sniper for an extra pair of eyes and ears and help incase the sniper gets ambushed. If the playing area is realatively flat and the trees are too dense to be a reliable high point be ironic and set up in a hole at the end of a trail. Wait for an attacker to get in range then pick em' off as they come.
Step 4: Offensive Tactic
Playing on the attack team is my favorite part of airsoft. Some reliable tactics that I have used in the past is to split up into 3 groups. A fairly large group that will go up the middle of the playing area. And two equally sized groups that flank up along the sides. IMPORTANT: Keep within each groups sight so you can use hand motions and not have to yell. This will make it easier for the side groups to sneak up and catch the deffenders on surprise.
Step 5: In combat
If you in combat and you see the other team starting to flank you TELL YOUR TEAMMATES. You have a better chance of holding them out if you hole team knows whats going on. If you are being overun retreat to a better location. You then can regroup and the other team will be forced to rethink there strategie. Always keep your eyes on the target(s). If u duck down or turn ur back to a tree you could miss an enemy moving and this could result in death!