I'm surprised it took so long for someone to post the right answer. The right answer is to go with the cheapest modifier, which is usually cold/lightning. Poison/arcane is cheap as well. You'll be paying a fortune to stack physical or fire.
And yes, your items should have resist all and the specific resist. Pro tip: dont ignore intelligence. Always factor in the resist all granted by Int. I have gloves with 68 res all, 50 cold res, and 180 (!!) int (plus dex/vit), for a total of 136 res all on 1 piece.