Starnow.com has provided me with most of mine - I prefer it to modelmayhem when I'm looking for kids, older people, quirky people, etc, because I find that there's much more variety. That said, modelmayhem.com is great too, especially for nude or fashion models
ModelMayhem and also Craiglist. As you reach more and more people, you won't need to look anymore if your photography is good, people will come to you!
It isn't rocket science. You just walk up to people and ask them. It isn't a big deal. You can also leave "models wanted" notices on bulletin boards (with pay rates and contact information) and so on. As Photomark says, if you can't bring yourself to do that, you need to get into something else. People to ask that are "target rich" are art students, gym members, theater actors, dancers and so on.
There is realy only one way and that is to simply ask people , have some cards made up to hand out with your contact info on them , ask the people you meet in your day to day life, do a search to see if there are any photographic clubs or society's in your area.
If you realy want to photograph models then dont be shy. Photographing and finding models takes people skills and a lot of patience , finding models is one thing , getting them to show up for a shoot is another.
If you are the shy type then do landscape photography
I want to do more to get a better portfolio going, but it's so hard to find people who are willing to be my subject. So how do you find people?
I also don't have any family, and very little friends in the area because I haven't lived here long.