All those tips below are indeed useful, but that's not what the OP was wanting to know. Technique won't help you when you need that extra bit of forgiveness a better sensor provides. The 5DMkII has a significantly better sensor hands down. The 7D is one heck of a noisy sensor even at ISO 200 when the exposure isn't perfect. Silly me thinking that if I bought a new 7D, there would be improvements to the image over a 2 year old version. I was wrong. In fact the new 7D has just as poor AF, just as poor noise and in fact a few new artifacts, vertical banding and in video mode, rolling hum bars! Yup, DPP knows how to get rid of the vertical banding but sadly, there goes the image definition. Gee whiz, I must have got another dud!
Use a sturdy tripod.
Use a cable release.
Use mirror lockup.
Use the proper aperture.
Use the proper shutter speed.
Focus properly.
Shoot in best light.
Use good lenses.
Clean your filters.
Clean your sensor.
Clean your lens.
Use a lens shade.
Expose properly.
Sharpen properly (for the dedicated output).
Understand and use color management.
And a dozen other, seemingly obvious, details. Following such technique will be far more beneficial than choosing between those two excellent camera bodies.
Tutorials can be found in abundance on the web. Not all are correct. Not all will pertain to your images. My favorite tutorials are available at luminous-landscape. I'm more comfortable with video tutorials than books. Video first, then books - that works for me.