There are many events you need to know about to save resources for the right time. Most of them are cyclical and come back regularly.
During Double Refinement events you can earn twice as many refinement and enchanting stones from many sources.
The most notable source of enchanting stones is the Dread Ring campaign. In lairs, you can get up to enchanting stones rank 5. You can buy Thayan Lair Keys for 10 Vanguard Scrips in the campaign menu (you get them by completing quests in Dread Ring). You can also exchange Onyx Fragments (currency you get by killing monsters in Dread Ring) for Vanguard Scrips at the Bounty Master in the Dread Ring camp. When there’s an event, go to the Phantasmal Fortress lair (it’s the easiest to farm) on a Thursday, Saturday or Sunday after the event reset time (events reset at a different time than everything else and lairs are on the same clock). You cannot get enchanting stones the other days from this lair. Farm the lair (make sure you get 2 enchanting stones), make more keys with the Vanguard Scrips you will get at the end of the lair, go back to the Bounty Master to make even more keys… and do that until you have no more keys, Vanguard Scrips or Onyx Fragments. You should have tons of enchanting stones by the end.
Enchanting stones rank 6 loot regularly in the higher end dungeons and trials which require 17k item level or higher. Save reroll tokens (vip rewards) for these. You can get 4 at a time if you are lucky and have a key for the bonus chest.
Double Guild Marks
During these, you can can earn double guild marks from anything you give the mimic at your Stronghold. Guild Marks are mostly used to get explorer charts for masterwork materials (you can sell them at a very good price if you are not interested in crafting), but you can also buy overload enchantments, food, … or some gear from the Mysterious Merchant (temporary structure, ask one if there’s none in your alliance) !
Farm Influence as often as possible (especially during double influence events). You only have to beat 5 encounters in your Stronghold for a maximum of 400 Influence (doubled during double influence events). The easiests to beat are Beast Attack!, Demon Attack!, Spider Attack! and Drake Attack!. You can also beat one Tier 3 encounter for a bonus of 10 Heroic Shards of Power, the easiest being Giants among the Dead (No Sympathy and Beholders are also soloable if you can move properly). There’s always at least one easy encounter available. If you are looking for an easy Tier 3 encounter, you can also look in the other Strongholds of your alliance.
During 20% Guild Mark sales, you can buy anything you want, be it the Executioner’s Black Guarbs or explorer’s charts.
15% Sales in the Wondrous Bazaar
If you are VIP 12, that’s 40% off ! Buy marks of Potency during that time to save some AD.
30% Sales in the Zen Market
There are regularly sales in the Zen Market, especially on the Anniversary (June), on Black Friday (November), Winter Festival (December), and from time to time on other occasions.
Summer and Winter Festivals
During the Summer and Winter Festivals, you can share gifts with others to get plenty of rewards (wards, companions…). Grab a gift every day on every of your characters and share them with friends to get tons of good stuff.
Any Other Event
There are often good mounts or companions available during events, like the epic Enchanted Broom mount available during Halloween. Make sure to grab them if you can ! Participating in events is usually a very good idea. There are events for end game players, but most of the events are accessible to everyone.