The most obvious thing to do is fill up your roster with high level guild members for guild battles on Castle Age. As a new guild, that can be difficult to do, if you do know a lot of high level players. At first do not worry too much about levels. Even if the lower level guild members cannot win a fight, they will still be able to contribute. The key to winning is coordination of the guild.
If you have a small guild, keep everyone in one gate in the guild battle on Castle Age. This will allow the clerics to heal everyone. As you grow, spread out the groups evenly by class. Fill up one gate at a time, pushing your lowest levels into the next tower first. This may mean that the lower levels die first but they may have to take one for the team until you fill up the roster on Castle Age Guild Battles.
Active clerics are the key to winning guild battles on Castle Age. You will need several clerics in each tower in order to continue the fight. A good attack is critical to the cleric. If your clerics are not winning fights, then they will not heal their tower. Mages also need a high attack to win and use their special ability. Since each win damages all in the tower attacked, you defiantly need a mage or two. Rogues are good for taking down high health opponents. They also need high attack. Warriors are usually for inactive player in your guild, high health is great but the other classes usually offset this by their special abilities.
Coordinating Your Efforts
Be sure that your guild members know when you are going to have a guild battle on Castle Age. This way you can have as many fighting as possible. If you are able to have the majority of your guild in on the fight, you may be able to kill a guild before they know you even attacked! The order of attack should be by class. Mages go first after the highest number of players in a tower, since they damage everyone in a tower they should go after the weaker ones they know they can win against. Your rogues go second, focusing on the highest level they can safely win against, stunning enemy clerics first if possible. Then any warriors fight also focusing on the clerics. And last the clerics go again attacking only those they can win against. If your clerics rotate through attacks and fight a minute apart or so, they will continue to heal each other as well as the rest of the group.
Even the Fallen Have a Use
Since inevitably people will get stunned in the fight, you can still win the guild battle on Castle Age, even if you have all of your clerics stunned. Once the low levels are stunned and cannot be healed, they should attack the highest level opponents to weaken them. If several of them swarm one enemy, they can take him down. This leaves the weaker enemy members to your more powerful members. As you fight, even losing gets you guild tokens. The more you fight, the more guild coins you get at the end of the battle. Use these coins to get better skills and even a general. Also, as a side note, be sure to have your best general in place and the better items you have the better you will do, even at low levels.Get all of the Demi rewards as well as those will give you better odds in the guild battles.