Gatherering is the True Endgame...

[Lemuria]

I still haven't even figured out how to use those collector's skills yet. Every time I try, the mining/harvest options all go dull and can't be selected.

[Keylus]

I still haven't even figured out how to use those collector's skills yet. Every time I try, the mining/harvest options all go dull and can't be selected.

You need to active "Collector's Glove", if you don't have that skill then you need to do the quest "Inscrutable Tastes" at Foundation (X:10 Y:10) NPC: Morgayne

Afaik, you can only collect items from the new unspoiled nodes

[Zetsumei_Tsunarashi]

I still haven't even figured out how to use those collector's skills yet. Every time I try, the mining/harvest options all go dull and can't be selected.

Only certain items can be made into collectibles. If everything in the node is greyed out with collector's glove on, then it means that none of those items can be made into collectibles.

As stated above, most collectible items are found only in unspoiled nodes, but there are also a special new type of node called "Ephemeral" node that also has special collectible items which can be used with the skill "Aetherial Reduction". This is a sort of gatherer's desynthesis that relies on the rarity of your collectible to determine the yield of the aetherial reduction.