One of the best ways to get silver in Realm of Empires is to raid neighbouring Rebel Villages. Here's how.
1) Let your Clan know which village you're attacking so that other Clan members don't raid the same villages
2) Send out spies to neighbouring rebel villages to find out their strength
3) Run the battle sim to make sure you'll survive the attack
4) Send attack - you will lose troops in this attack and you probably won't make up enough silver to make it worthwhile this time but that's okay. The silver mine keeps producing even when there are no soldiers guarding it
5) List in the Village Note that you've attacked this village and (I even make a note of time and plunder) - then set the highlights to show things that say your name in the note so you can keep track of the attacks
6) Send out wave after wave until the spies tell you the treasury is empty - rebuilding your troops with the proceeds
7) Then, once you've cleared it out (I always send spies with my attacks so I know what they've got in the treasury), eave it for a day or so before attacking again. The treasury will refill and there won't be any defending troops to kill so you can just walk in and walk out with the loot.
Citizen Militia Carry: 50 pieces of silver
Infantry Carry: 40 pieces of silver
Light Cavalry Carry: 300 pieces of silver
Knight Carry: 400 pieces of silver
Ram Carry: 0 pieces of silver
Trebuchet Carry: 0 pieces of silver
Spy Carry: 0 pieces of silver
Governor Carry: 0 pieces of silver