I use frelancers periodically. If they're not from my local area, they tend to be people I've run across in various forums/news groups whose style I liked - meaning they answered questions in a technically proficient mature manner and seemed to have a commitment to accuracy and have been in the group for a while.
I pay freelancers that I haven't had a lot of experience with a percentage upon some milestones being completed and the remainer upon completion of the project. Freelancers I've worked with a lot get paid like I do - a percentage up-front (to ensure their commitment), something for my contracted milestones, and the remainder when I get paid upon project completion. Don't think a good one would work with me again if they had to wait 3 months to get paid.
You need to know how to get the money to your country. This can be difficult and I've dropped people who it was to hard to pay. Do your homework on this.
Don't offer to do "anything". Usually means you're not an expert in anything. Identify your core compentencies and join forums/news groups who cover them. Get yourself known there. Note that many of them have policies about advertising your services. Read the FAQ and lurk for a bit.
I stay away from the freelance boards. To many wannabees there. The Boss's advice about getting involved with a reputable project is a good one. Lots of open source stuff out there looking for people to help. Pick one that has commercial potential or that will be used as a component on many web sites.
Basically, you get work based upon your reputation and its up to you to develop a good one in some visible places.