Tips resarcana

Basic Strategy

Don't put too many artifacts into play. Putting 4 or above is usually a bad idea.
Don't think the game is all about the essences. They are useless unless you can convert them into points.
You should discard cards you don't need to get essences you want to play better cards.
Get a place of power early--their powers can aid you to victory.
Don't afraid to pass early if it can give you a magic item that you want.
Dragons are not good ideas, but if it can break your opponents' plans, that will be hell to them! To counter, just keep some life, and in 4 player games you should expect at least 1 dragon. Dragons can also score with Dragon's Lair or Sorcerer's Bestiary.

Alchemy: Not an effective exchange. Only use it when you really need that 2 gold, e.g. buying a mounment or place of power.
Collecters (calm/elan, death/life): Good in first turn if you want to buy a place of power or a good artifact.
Divination: Usually of no use, as you gain nothing. However, you can use it to cycle out useless cards with cards you want.
Protection: Usually of no use as attacks and dragons are not common. But if you notice potential attacks that may break your plans, grab it.
Reanimate: Very useful when you have a matching artifact or place of power. However everyone wants it, so get it before your opponents.
Research: Basically, it is exchanging 1 essence for 2 essences or 1 gold. You can use it to dig for a card, but Divination is better for this. Or you can play it if necessary, therefore it is worth about 2 essences.
Transmutation: Offen of no use as the game provides lots of methods to exchange essences. However, if you have none of them, try this.

Chalice of Fire: The collecting ability pays off in turn 4 even if you don't use it, and its reanimate is useful with many places of power.
Chalice of Life: This strong essence generator feeds itself and doesn't need to be turned. Best with Sunken Reef.
Corrupt Altar: Expensive, but you can play expensive cards, use it once then sarifice it. If you are tired, just sarifice the Altar itself.
Crypt: You can discard a card then resurrect it with a discount. Crazy with a sarifice card. Don't need it? Then get 2 death instead.
Dragon Teeth: Feeds itself and discounts you on dragons. Although bad with places of power, it is best with Philospher's Stone to get gold.
Horn of Plenty: Much above average. Pays itself off with 2 turns. Fits itself into any strategy. First pick in nearly all draft.
Mermaid: You can use mermaid to score while using other abilities of places of power. Better then a novice would think.
Vault: It's cheap, it's flexable, it can be aimed for small or big! Good with both gold and essence strategies.

Bone/Fire/Water Dragon: Expensive, but easy to dodge. Better to discard for essences.
Dancing Sword: Its collecting ability only pays at turn 4, and if your opponents see this, they won't play dragons and makes this useless.
Elemental Spring: The cost is steep, and after 3 turns it is just 0. Most attacks can be prevented by an essence, so this is redundant.
Hand of Glory: Your only gain is just 1 death, making it even in 4 turns. Only slightly better if the cost is mitigated.
Windup Man: Worst card in the game. The cost is high, and it is slow to pay off. While you are waiting, the engine is dead and you have spent a bunch of essences for nothing.