Instructions
Speak to an Herbalism trainer in any faction capital to learn the Herbalism profession and Herb Gathering skill. Find and collect herbs throughout Azeroth until you reach level 525 in the profession. Gather herbs within your current Herbalism level range (which are marked with orange or yellow labels) to receive the largest experience bonuses and raise your profession level efficiently.
Travel to Orgrimmar or Stormwind City -- the capitols of the Horde and Alliance factions, respectively -- and locate the Earthshrine containing the Twilight Highlands portal. Orgimmar's Earthshrine is located on the north border of the city near the zeppelin towers, while Stormwind City's Earthshrine is located directly northwest of Stormwind Keep. Right-click on the portal to enter the Twilight Highlands.
Click the magnifying glass icon on the edge of your mini-map in the upper right corner of your game window. Check the "Herbs" box in the drop-down menu to enable herb tracking. Watch your mini-map for yellow dots (which indicate herb locations) as you travel.
Go northwest from Dragonmaw Port toward Thundermar, following the long line of cliffs south of Kirthaven. Turn south at Thundermar and follow the mountain range through Victor's Point until you reach Crushblow. Travel west along the edge of the Obsidian Forest until your reach the coastline directly opposite Highbank.
Travel northwest to Bloodgulch and follow the northern riverbank back to Dragonmaw Port. Repeat this loop as necessary until you have accumulated the desired quantity of Twilight Jasmine.
Return to your faction capital and enter the portal to Tol Barad in the city's Earthshrine. Press "B" to open your inventory and right-click on your fishing pole to equip it. Travel along the Tol Barad coastline and search for round, sparkling patches in the water, which indicate fishing nodes.
Press "P" to open your spell book. Click on the Fishing skill or press the assigned hot key to cast your lure into the fishing node. When your bobber dips below the water's surface, right-click on it immediately to reel in your catch. Each time you successfully fish in a Tol Barad fishing node, you have a chance to receive Twilight Jasmine.