I've been chelating for a few years now, and my health has improved a lot, though I'm not ready to stop yet.
The two methods I've used are cilantro and chlorella and the Cutler Protocol.
It's important to note that you shouldn't chelate if you have any silver fillings. That would likely make you much worse. Replace the fillings before you chelate. It's a good idea to replace the fillings anyway since they are about half mercury, and the mercury flakes off into your body.
Cilantro and Chlorella: This is the method I started with and have started using again after a couple of years of using Cutler. There are people who question the safety of this method, but I haven't had any trouble. I have a friend who uses it too, and she hasn't had any trouble either, in fact, she is very pleased with the results of using it. Actually, I experienced my most obvious improvement using this method (more obvious than when I was using Cutler). The downside is that the side effects I experienced while using this method were generally worse than while using Cutler.
I take cilantro spice every four hours or so with chlorella, including waking up around 4 AM to take it again. It's important to use them both because cilantro is not effective without chlorella. With this method there really isn't a set amount to take. I take a few dashes of cilantro and about 6-10 small tablets of chlorella each time. You can do this for a few days or a week before taking a break. Continue to take the chlorella a few times after you take a break from using cilantro.
The Cutler Protocol: This method is laid out very clearly by Cutler, so there isn't as much guesswork as Cilantro. As mentioned, the side effects weren't as much, but this method also seems slower.
The protocol uses the supplements DMSA and ALA for chelating. You take DMSA every 4 hours, including waking up at night to take it again. Do this for 3-5 days before taking a roughly equal break. You do this for a few months and then start taking ALA every 3 hours (either with DMSA or by itself). I've read people who just use ALA without DMSA because DMSA is expensive, so I guess that's possible too. If you replace any silver fillings, make sure you wait 3 months before using ALA.
It's good to start off with smaller doses when you begin chelating. You can then work your way to larger ones. I've also found that taking doses more frequently (hourly during the daytime) has also worked quite well, but I wouldn't do that in the beginning.
This is a overly simplistic rundown of Cutler. A Google search will reveal more information, including how much you should take each time. Any oral chelation should be done frequent-dose, including at night to avoid redistribution and keep the effect going.
Drinking a lot of water, visiting a sauna regularly, taking selenium, Vit. C and E, and zinc, eating foods which encourage glutathione growth are all useful for chelating as well.
It's really important to do as much research as you can about chelating before you begin. It's not something which should be done without a firm base of knowledge about how to do it and what not to do.