How can utilize to my advantage a farm account?

The idea of a farm account is to produce rss for you to take and use. Make sure the farm account is a farmer for increased rss production or trader for increased money production (you have to be a raider to take money though).

Upgrade the base and production buildings to a reasonable level (12-16 ish or more) to make sure it is producing rss and make sure the warehouse buildings are up to a level you can get a good store of rss.

Keep the farms accounts in a farm alliance that your main alliance is protecting so that other don't attack them before you do.