GW2 tends to suffer from the same thing every other game in history suffers from: “I sent you in there to save the princess, and you struggled with hours of fighting and finally defeated the boss, completed the dungeon, and brought her back, let me reward your valor with this weapon that will make that dungeon easy, should you ever want to go back in there.” Basically, the materials required to craft level 50 items are located in areas where you need to be at least level 50 to not die in 1 hit.
As was said above, the guides to 400 will still work fine, but weaponsmithing and armoursmithing are an awkward combination unless you hit the ore nodes really hard, and even then fine materials will be a problem. I would advise swapping one craft with cooking.
My advice is to just refine materials until you are about level 18. At that point get your crafting up to 75 and you should be able to set yourself up with masterwork (green) equipment for level 20. This should also clue you in on how crafting works, so next time you’ll be able to do it more efficiently.
The points you want to look out for are levels 20, 35, 50 and 65 because at each of these points you can craft masterwork (or even rare for higher levels if you’re keen) equipment. It’s how I did it when I leveled my alt’s and I rarely had to buy materials.