Think outside the bo a bit as well. Almost all the outfits you see in steampunk, are upper class, clean and primped, proper ready to go to the club, ball or whathave you social event or location. Making a more working class, poor, or street level outfit, one can get more clever with items and materials.
For one thing, you want worn in, rattier looking clothes, that have seen perhaps more than thier fare share of days. Sticking with a more British/European centric view for the moment;
Tan, brown or black slacks or cargo pants, faded and roughed some, perhaps even cut off rough at the ankle or below the knee. It's perfectly ok if they have a few holes or sewn in patches. Well worn in loafers, oxfords or boots (preferably boots), though well cared for worn in footware makes sense too, footware being the highest in cost and hardest to replace item, they would be like to see a lot of loving polishing and the like. Of course a belt, but it can be old and beaten up, mismatched in color, or even non leather. Perhaps it is too big, having been found, or left over from better days, and the buckle might be simple, or worn, perhaps pitted and unpolished. A dress shirt, again one well worn, and if you have to get a modern one to use, either a used one or new and in need of aging, go with something too large for you, the sleeves will appear poofier, so more of a victorian cut, and the not quite fitted look is appropriate for the poor. If you plan to cover the buttons (see a litt further on) any buttons will do for the front, though whatever ones show, you may want to consider changing from plastic to soemthing metal or wood. I would suggest a sweater or the like over the shirt, something older and in a slightly ratty state, perhaps cut off the sleeves half way from the wrist to elbow. I also plan to play with a hooded sweatshirt some to see how I can get teh look down. I also suggest a slightly large or small waistcoat or vest, over the sweater or the like, or just the shirt. Fingerless gloves, a lower class hat, perhaps a slop front or a bowler... Then, dirty the whole thing up some, staine from sweat and dirt and grease and teh like. Not too much, but enough to show wear and no money to replace. Now yo uadd some accessories to show tools of a trade, or just trinkets you carry, and viola!.
