Alright now while this thread may have been posted before and yes i've had a search i couldnt find anything so the time has come for me to put my info forward.
Firstly because its a fishing guide its generally a good idea to have 375 fishing. This can be done a number of ways, jumping from spot to spot fishing i reccomend fishing outside of wailing caverns to level it up. I did this and made a good load of gold along the way from deviates. While its a pain in the ass to grab the quests and finish them off its worth it. My suggestion might be because it takes so long to level fishing use a box such as the Pirox Fishing Bot PiroX Bots - pfbInfo. Setting it up is fairly simple and works really well, however i will suggest a word of caution when using the bot and be sensible. The people who get banned are the ones who leave it running for 2 days straight. If your worried about people reporting you just jump in the instance and fish inside there. The next step is to fish deviates for as long as possible, the rate of deviates is roughly one in four so get as many as you can before dieing of boredom and then head over to the auction house. Hopefully you have some form of cooking skill, and can grab the savoury deviate delight recipe from the auction house and cook from there. Depending on the server you can get 20g per stack of 20 however a smarter option is to sell in stacks of 5 at 1g each. People only want to buy small stacks so 5 is a better option.
My second point is primal water. While most people are aware of farming on the elemental plateau they rarely find the time to get there. However my suggestion is once you have your fishing at 375 plant yourself at elemental plateau and farm the pure water for 10 minutes at a time, flying round looking for the pure water. It takes roughly 10 minutes to fish the whole area and in that time u should have about 3 primals. Depending on the server they can sell for between 25g and 30g. Among the other junk you will occasionally get. After finishing this off fly up to one of the islands and log off or do what you want. Basically the pure water respawn roughly every 45 minutes to an hour. So go away and do what you want and come back.
So in conclusion take 10 minutes out of your day to fish the primals and walk off simple as that making an easy 90-100g. Keep it in mind next time your thinking of how to make money.