If you have not done your research o the game and its market, you may just pick a profession to level at random. As Weaponsmithing will show you, that is a bad idea.
With the decreasing availability of metals, and the complete lack of enough higher tier nodes, Weaponsmithing's cost to level is skyrocketing with every day that passes. Literally, the materials are getting more and more expensive by the hour due to supply not being able to meet demand. You may go and check the AH and check the pricing of Orichalcum Ore, and you'll be shocked to learn of how expensive just a single piece of it is.
At the moment, on Eden (NA-E), Orichalcum Ore is going for 2.0g a piece. Now, to get from level 150 Weaponsmithing to level 200, you would need to make at the very least 865 Orichalcum Round Shields. This is by far the most efficient way to level in terms of time, but not in terms of money. However, with each level taking around 75k+ XP to fully level up ONCE, there is really no other viable option, as both star metal AND Orichalcum are very expensive, and Starmetal levels noticeably slower than Orichalcum.
So, you're either spending weeks of your life gathering not only 34,600 Orichalcum Ore, which is always contested, as well as Platinum Ore, as these are the numbers needed to achieve the level cap, or you're spending an upwards of 82.6k gold on the resources to level from 150 to 200.