Since I've lost a good amount of weight already, some of the old clothes I used to wear are too big now. I have given some away to thrift stores and to the salvation army as well. Any clothes I deem as crap is tossed away or used as a cleaning rag. A big cleaning rag lol.
I usually keep them in case I get fat again. Lol just kidding. So far I haven't done anything with my old clothes yet. But we have a St Vincent DePaul store here that accepts donations, so some lucky guy or gal is going to find some nice clothes in their sizes.
I've sold some, kept some for sentimental reasons and then gave most of the rest away. A lot of my old clothes were outdated as well, so it wasn't too tough to get rid of most. I do donate most of my clothes though.