I have to admit that most of my clothes come from thrift shops, or consignment stores and are second hand. I didn't mention going before because they generally do not have a very good selection of larger clothes. The smaller sizes are better.
However, don't give up. I make it a habit to scrounge through the racks about once a week, and often come up empty handed. But being persistent is the key to shopping at second hand stores. I also have great finds...this week I have worn thrift shop finds every day to work - London Fog, Dior, etc. The clothing is expensive but the price I paid is not and noone else is any the wiser. I think the most I paid for a suit was about 15.00 (and that's Canadian
).
Also, try to find out what day/time they usually put new stock out and try to be there when it is placed or shortly thereafter. That way, the good buys won't be snapped up before you get there. I have been shopping at one of the thrift stores so long that the staff phone me when they get good stuff that they think I might like. You can always develop those kinds of relationships as well.
Also, about the fitting rooms...I don't try clothes on in those places because I just find them on the too grubby side overall. I have an agreement with all the stores that, if they don't fit, or I don't like on, I can return. When there is no fitting room, you would think that returns would be a standard practice. Also, the clothes tend to unwashed, so I try them on at home wearing a skin tight leotard and stockings - just makes me feel better.
Be persistent - it will pay huge dividends in the long run.