What are your interests? The easiest way for me to meet someone is over the internet, so messageboards and the like are useful. Let your location be known, so maybe you can find people that live around you. I also like to look in the newspaper... not at the personals but at the calendar. I find something that catches my interest, and I attend either hoping to meet someone (which works... sometimes...) or I invite someone who I believe shares the interest. When I first meet someone I don't know what I'm supposed to do, exactly... so I figure, I should take control and invite them to do something, instead of waiting for them to invite me to do something... which they actually might be doing but I'm not understanding the invitation (for obvious reasons, yeah?). But I'm afraid of boring them, so I try to find something good to do.
I find becoming a member of a casual organization (like a club or whatever) kinda difficult to handle. They're quite clique-ish, except with a specific interest. What I like doing instead is to join something more organized, where I can have a clear position and responsibilities. It'll be more broad (like volunteering at a museum, library, doing health care, social work, ect.) but perhaps there are organizations like that in the areas you are interested in?