I'm sure other people have a different take, but my advise is to stick to perishables. Potions, varnishes, and if your feeling really ambitious arrows. becoming a master level craftsman in something like smithing, leather working, and or carpentry is a black hole of time invested relative to gain either EXP wise or financially. To use worst case scenario a TEMPLATE for plate armor costs 1000 to 2000 gold and for the finest ones the DC is going to be in the low 50s. To get your skill that high you are going to spend a minimum of a year real time doing little besides carrying several hundred pounds of ore to a smelter and praying the random number generator for success doesn't do its normal bullshit of rolling 25% lower than what the theoretical success chance is. With things like herbalism, and alchemy they both level relatively fast and there is a constant steady demand for things like potions and varnishes, but each player is really only ever going to need one weapon and one suit of armor. You will never come remotely close to recouping your investment in time and materials with these things. Basically crafters ultimately do it because they like it. Don't expect to derive any advantages from it however.
I know the theory is that people will band together to form crafting parties, and I've even seen a few but basically if you give players the chance to go role play with you while your collecting some gargoyle pelts and mine ore all day for no treasure or EXP or run off to Harakir to farm trolls for an hour its no contest what their going to do. My oldest character is 6 years old (in real life) and he is a master level craftsman in Leather working, leather curing, leather boiling, herbal ism, alchemy, smelting, smithing, and high enough in carpentry to make strong alchemical steel tipped arrows and hes 15th only level. There are players who are half his age who passed him in level years ago basically because they don't waste all the time in crafts. Moreover say goodbye to ever being around for any DM events since your always going to be in the bottom aof a mine or carrying around several hundred pounds of crafting garbage you just spent the past few hours (again in really time) collecting to just safely drop.
Again. I'm sure others have a totally different take on this. I'm only telling you what my personal experience with it is.