Adam Hughes uses Copic markers, and he's happy to share how he does so. You can check some of that action out here: Adam Hughes Copic Marker Tutorial. Otherwise, there are plenty of videos on YouTube where your fellow artists share techniques as well. A search will bring up enough to keep you occupied for hours on end. Many of these videos hail from the scrapbooker's end of things, so you may find a lot of ducklings and pixies and other cutesy subjects. Even those have their merits, however, if the creator of the video shares details on technique.
To make a long story short, think of the watercolor approach when you use these markers. Light to dark with some leeway on blending with a marker made just for that purpose - the #0 Colorless Blender. Paper plays a major factor in the process as well. You'll hear lots of preferences for this type or that type, but in truth it's whatever you're comfortable working with. I've read that marker illustrations are best done on marker paper, but I had some success with plain old Bristol of around 92 lb. weight or so.
Below is a sample of my attempt to mix a flesh tone. I wrote down all the colors I used, though not necessarily in the correct order. I did a lot of swapping between the R000, R00 and R01, then I went in with the E00 and the E02. Lastly, I covered it all with a layer of E70 because the end result looked too 'peachy' to me.
The E 37 Sepia wasn't really involved in the mix. It's there because it's The Marker That Would Not Die (a story in and of itself) and I was scribbling with it first before I tried anything else. And the blue blend near the top is an attempt to apply the #0 Blender. In truth, I'm thinking for a smooth transition from dark to light, some of the really light tints may be required. Not sure, still playing around as of yet.
Do you have some favorite Copic techniques, or do you prefer another marker? I'm listening.