In SvS most enemies are shielded, burned by purge, or intercepted, so finding attackable targets is hard. BEST method: Event Center > Server War > Ranking of Enemy Server > Alliance Power Ranking > pick an alliance > View Members > find members with the 'Golden Sword' symbol (means they are currently on YOUR server) > Detail > Locate Coordinates (consumes an Arrest Warrant, otherwise costs gems) > teleport in and attack. Fighting an enemy who is on your own server = relative advantage (you can shield, and they get fewer reinforcements). Golden-Sword players usually leave your server quickly, so search immediately; players who stay a very long time are likely decoys - note and ignore them. Before spending an Arrest Warrant, check around your own temple (you may find enemies for free) and watch world chat for decoy intel. TIMING after locating: do NOT teleport if the enemy has an orange shield (teleporting onto a server auto-shields for the first 5 minutes); if no dotted march line extends from their city, wait and teleport only when they are out attacking a monster/city (so they can't escape) but land just before their troops return home (else they call friends); if there are no cities near them they will likely re-teleport away.
Original research source: Evony Guide Wiki