For the most part, this is done with stone, saving your copper and bronze bars until later except when you need to equip yourself or your friends or clients. Make Rough Sharpening Stones until you reach 25 and learn Rough Grinding Stones. Make Rough Grinding Stones until you reach skill 65, keeping them for use later in making other items. Make Coarse Sharpening Stones until you reach 75 and are a Journeyman. Copper items useful as skillups include Copper Bracers, Copper Chain Pants and Copper Chain Belt.
There is no one best path up because it depends on which dropped plans you get a hold of, which specialty you take, and which items you can make for guild mates or sell that give skillups, which will vary by guild and server. It also depends on whether you learn every plan going up or only the bare minimum because you are trying for a truly lowest cost or fastest power-levelling run up to 300. The path I outlined is a fairly optimal approach but it does include obtaining some dropped plans at the right times.
You will want to equip yourself and and your friends as your skill raises. If you keep your skill at 25 plus five times your level then you will always be able to make items you can equip at their minimum level. Outside of the items you make because you want to, or to fulfil the Blacksmith quests, there are a series of minimum-material items you can make to advance your skill, mostly consisting of stone, misc. items, and some low-material armour items.
Statrting at 150, make Rough Bronze Leggings until they turn grey at 175. Iron Buckles are easy but turn grey at 155, while Golden Rods turn green at 155 and grey at 160. Golden skeleton keys are green when learned and grey at 170. You will want to equip yourself and friends with the Green Iron Set and that will provide some skillups. If you are lucky enough to learn the Iron Shield Spike plan at 150 then you can make and sell these at a good profit until they turn green at 180 and grey at 210. Another profitable drop is the Iron Counterweight, green at 190 and grey at 210. At 200 you learn Solid Grinding Stone so make those until they turn grey at 210. To get from 210 to 225, make Golden Scale Bracers to 215, then make Steel Plate Helms to 225. You will also be equipping yourself with the Golden Scale armour set and the Moonsteel Broadsword is required for a quest in Duskwallow Marsh. A number of expert weapons and armours are saleable, including the rare Green Iron Hauberk at 180.
The faster you try to skill up, the more it will cost you because you are likely going to have to vendor much of it. The market can only absorb so much of any one item. Whenever possible, spread out the items you make over time or make a variety so that you do not overload the market. If you want to minimize cost by selling your items, look at the Auction House to see which desirable green or blue items that give skillups are lacking or in short supply and go for them, bypassing those that are in large supply already.
At 75, you learn Coarse Grinding Stone, which are green when learned. Make those until they turn grey at 100 and save them for making further items. Turn any tin and copper into bronze bars but save them. Make Silver Rods until they turn green at 105 then make Rough Bronze Leggings until they turn green at 145 or even to grey at grey at 175. These take 6 Bronze Bars and sell to the vendors for 9.62 s each, so if you can buy stacks of 20 Bronze Bars for 30 s or less, you can actually make a profit while you skill up. Also at 125 you learn Heavy Grinding Stone. Make these until they turn grey at 150 and keep them for making other items. If you are able to learn the Deadly Bronze Poniard dropped plan at 125 then you can make and sell it at a profit until it turns green at 155 and grey at 185. The Patterned Bronze Bracer is required for a Badlands quest. At 145 you learn to make your first rare item, the Shining Silver Breastplate which sells well.