I know sooner or later I will get attacked, what is the best way to minimize my loss of rss and troops?

Being shielded will stop attacks although this is hard to do all the time. Being a farmer class will give you a limited amount of protection for your RSS. But only if you are happy with this class choice.

Your rss is stored in 2 places. Listed at the top of the screen is the rss you have in the warehouses. This is vulnerable to raiding and its a good idea to use this up when ever needed to keep the stocks low. The rss you have from rewards in boxes in your inventory is safe so keep this stored until you need to use it.

Troops in the legions can be set to not defend your base it attacked. This is done in the Fortress Building under Garrison. You will still loose some troops though even when you do this. The only way to prevent them being wounded / killed is by sending them away from your castle. Send them to gather or camp a long way from your castle or preferable find an alliance member who is shielded and send them as reinforcements to their castle.