Level

Leveling up is the main thing to do on the Wandering Isle for its stayer-community. For levels 1-16 you gain experience from killing monsters. After level 16 the only sources of experience are Quests, Daily Quests and Herbalism/Mining.

Herbalism
Herbalism is a gathering profession based on collecting herbs from the ground. Herbs that can be found on the Wandering Isle are Peacebloom, Silverleaf and Earthroot. While there is no nodes for Mageroyal they can be herbed from the corpses of Thornbranch scamp at a low rate. This makes it possible to make some glyphs albeit at a slow rate on the Wandering Isle.

Peacebloom (map of all peacebloom nodes)

Silverleaf (map of all silverleaf nodes)

Earthroot (map of all earthroot nodes)

Mageroyal (map of where all the Thornbranch scamps spawn, it's about 3% drop after using herbalism on their corpses)

From the maps above we can see that the best exp / hour place to farm herbs are Singing Pools. You can also get Peacebloom, Silverleaf, and Earthroot from Thornbranch scamps but if you're after just those you're better off gathering them from nodes.

Collecting herbs does not break Shaman's Ghost Wolf form, however Mining does.

Mining
Mining is a gathering profession based on collecting metal and stone from various nodes. The only Mining nodes that can be found on the Wandering Isle are Copper Veins.

Copper Vein Map (map of all Copper Veins)

From the map above we can see that the best places exp / hour to farm veins are Singing Pools, The Rows and Wood of Staves.

Quests
There is only a limited amount of quests, and the experience reward diminishes with each level. There is a total sum of 57 quests on the Wandering Isle, awarding in total 8520/12000 honored reputation with Shang-Xi Academy.

There are also a few account wide pet battle quests that can be completed once on your Wandering Isle Stayer and must be done on the main continents if you haven't completed these on your normal characters:
 * Battle Pet Tamers: Kalimdor Alliance Horde
 * Battle Pet Tamers: Eastern Kingdoms Alliance Horde
 * Battle Pet Tamers: Outland Alliance Horde
 * Battle Pet Tamers: Northrend Alliance Horde
 * Battle Pet Tamers: Cataclysm Alliance Horde
 * Battle Pet Tamers: Pandaria Alliance Horde
 * Battle Pet Tamers: (WoD)

Daily Quests
Probably the most time efficient way to level up. Although there are no daily quests on the Wandering Isle, there are pet battle quests on the main continents that can be completed by one character and turned in by another (for example a neutral pandaren).

There are 5 daily quests that can be turned in on any character:
 * Northern Barrens Completed on Horde character
 * Westfall Completed on Alliance character
 * Duskwood Completed on Alliance character
 * Cape of Stranglethorn Vale Completed on Alliance character
 * Redridge Mountains Completed on Alliance character

All 5 quests turned in award you around 32% of the experience needed to next level (adjusts with each level), so doing only this method you can get a level up in approximately 3 days. In higher levels (70+) it might be necessary to use this method, because you will only get around 1% of the experience per hour collecting nodes, and in levels 85-90 it might take a whole day of node collecting to get that 1%.

Experience
Daily Quests can cut down the time needed to level neutral significantly. Doing Mining and Herbalism on top of this would make for even less days per level. Heirlooms are never figured into these numbers since mail cannot be delivered to the island. It may be possible to adjust these numbers in the future when they add the heirloom tab.