Attack as a team. Focus on one DG to get a kill if you can. Capture flag, lock the flag with the flag locking device (250g in shop) go to the next flag. You need to do this soon, before you go way behind in warscore.

Small map-Forget flag capping. They can have all the flag, but they will have to deal with you and your tower, with you camping at the tower base. Only cap flag if you score a kill, then back to camping.

Big map-Flag capping spree. Avoid confrontation. Have your team ambush lone target trying to cap flag (you can often find opponent team doing that, due to your team's capping spree, and they need to catch up on flag capping which they thought they can split up to do it faster)

Also, don't buy new creeps (priest, angel, etc). Last thing you want is giving opponent more exp+gold.

turtle more or less , focus on getting 1-2 demigods really powerful vs demigods (for ex regulus/ub going atk items) and the other one focusing on you surviving .

when you get a kill use it to your favor by capping flags together and pushing back creepwaves ,

another good thing is to learn which items give the most damage/cost , the gloves for 400 for 25 damage is very good as is lightning thingie for 1500 and warlords punisher for 2250 . small cost to make your dps do a lot more damage , and the lightning (whatever its called) also helps clearing creepwaves and adds mana enough for another nuke.

as you turtle you deny them in creeps and get more gold yourself , upgrade gold inc at lvl 1 as soon as possible and keep farming theyre creeps, ordinary creeps cant push back your towers when you defend and if they get priests you get a big gold/exp gain .

warscore doesnt help them that much if they cant afford the upgrades. use the advantages they give you to the fullest more or less

well the only thing that easely breaches a turtle defense is catapults/giants , and on a small map that takes long time to get and on a large map you can tele around and snipe flags , i dont know what you are implying for as necessary upgrades , but mob health/mob attack should be the best for going on the offensive as priest give way to much of an exp/gold boost .

what upgrades do you think of then ? were talking about 5 mins into the game here so ?

I've had many comebacks since release, and most of them seem to come because my opponents made the mistake of continuing their gameplay style while pushing up to my citadel. For example, on crucible there is a high concentration of towers around the citdadel, so any enemy push is going to be short, but if you in turn ping one of their players and gain the upper hand, they have a very long way to run before they get to their towers. You can easily wipe thier entire team in 20 seconds or so after the first one falls in this manner as it will be 3 on 2, with their 2 sitting between the player who pushed out and chased one down, and the other two back in the base, and from there the entire map is at your mercy for ~20 seconds.

I think the same is true on most maps, but I guess unless you have a speed advantage you can't use this very well. Buy the Wand of Speed or something.

Obviously this is never going to work against good players, or if the level advantage has gotten out of hand.