Ok Ok I'll help you fella's out, lazy gits
I'm at work so can only type so much at a time before I have to alt-tab out, so gimme a few mins and I'll edit this post with detailed instructions!
Edit:
So I'm going to assume we are starting with 0 proficiency and experience with fishing (so others reading this who may have done no fishing at all can get going).
First thing you need to do is get yourself a fishing rod. The first rod that you can use is the bamboo rod, this has a 3 days timer on it after which it expires (3 days real life time, counts down wether logged in or out). These are pretty cheap to buy on the AH, about 3g on my server, but there is also a quest you get from a fisherman on the dock of Ezna (if you are Nuia side, not sure on the other side) which rewards a bamboo fishing rod.
Next you need to get yourself some bait and lures. These are purchased from the Blue Salt Brotherhood Merchant, which is in Windshade on Nuia side (sorry again not sure on Harani side, but sure you can find it). You will start with fresh water sport fishing, so you need to get yourself two types of bait for the different kinds of fish that spawn in fresh water. The first you need is Chum, which costs 600 vocation points, and the second is Chopped Squid, which costs slightly more (675 I think? Not 100% sure). Then grab yourself 20+ green lures, these cost 20 vocation points each.
Now you need to find a lake to sport fish in, on Nuia side go to the lake in Two Crowns, on Haranya side go to the lake in Silent Forest.
You need to look out for a load of seagulls flying around an area of the lake, this means there is a school of fish in the water there. Put your mouse over that area of water and it will tell you what kind of fish are there, check which of the two baits you bought earlier you need to use on those kind of fish. Throw the correct bait into the water (right click it in your bag and click the fish) and it will send those fish into a "feeding frenzy", this is when you can catch them.
I should also mention that there won't always be fish/seagulls on the lake, they spawn randomly. If when you get to the lake there are no fish/seagulls, hang around for a little bit or go away and do something else for 15mins, they don't take too long to spawn usually.
So equip your fishing rod and you will see the icon for the ability "sport fishing". Use this ability and click on the frenzied fish. You will hook a fish instantly, spending 100 labour, gaining 100 proficiency in fishing and 100 vocation badges. Now sport fishing is a kind of mini game, and if you are wanting to catch the fish you look for the icon that appears above it's head and you must click the same icon on your fishing rod ability bar.
But we aren't going to catch the fish at this stage. While you have less than 10k proficiency it takes too long to catch and will be a waste of time. Do nothing and after 30 seconds the fish will be released. Then you cast a lure again into the frenzied fish and gain another 100 proficiency and 100 vocation badges, at the cost of 100 labour.
Now as you probably noticed each cast is costing you 20 vocation points, but you gain 100 vocation points back. So each cast you gain 80 vocation badges, after about 8 cast's you have earned back the cost of the bait, and it has cost you nothing.
Rinse and repeat until you have 10k proficiency, and now you can set sail on the sea in search of seagull's ready to make some real money! Fishing will now make you a pretty good profit!
When you start catching them for profit rather than just to level proficiency, you will need to take the fish to the fish scales that are on all the docks in the game to claim your cash.