Start small.  Sell items from your own closet.  You will be suprised how many things you already have on hand that are in near perfect condition and you no longer wear or just don't fit anymore.

Be sure to take pictures, measure waist, inseam and rise.  Make sure to give a detailed description of what the item is.  Buyers can't tell if there is a spot, cut or tear from a picture.  Just be honest!!!  There are buyers that don't mind if there are flaws but they want to know what they are getting.

Buy from yard sales, thrift stores or clearance sales (such as Wal-Mart).  Try to buy in bulk.  Normally when you buy 20 or 30 pair in a variety of sizes you will get a much better price.  Just make an offer to the person you are getting them from.

Offer a discount on shipping if buying more than one pair. 

With that said; Be sure to check out my store:  The Jeans Lady