There is a subtle art to taking that which isn't yours, and it all boils down to the golden rule: Do that which is the least amount of work. Now, on to acquiring your very own instructable!
*See step 5 to claim dinner prizes
Step 1: Steal Original Ideas
~~In fact, this instructable idea was found while sifting through the forums.~~ I thought of this instructable entirely on my own. I know you're impressed.
Step 2: Copy and Paste Key Text
I must tell you someting. If you are stupid enough to actually try this (besides us, it was all in the name of science) and you get hurt, it is not my fault! You were the one that tried it, and I cannot control what you do with this information. Anyway, there are some much more dangerous instructables out there. So don't try try this if when you get burnt you'll blame it on me. Got it? So don't be an idiot.
Step 3: Take the Best Images (Or Create Your Own Really Crappy Ones)
Don't get too worried about the pictures creating interest, your sub-par instructions will ward off pesky questions. And besides, you'll be busy accusing people of stealing them, so questions aren't really of any concern. There are even more devious things you could do like changing perspective and/or color values in photoshop; but that's simply too much work and only amateur thiefs make such mistakes.
Another school of theft states that you don't steal thumbnails, but rather just take your own pictures. However, instead of taking quality pictures they should be blurry, obscure, dark, grainy and otherwise inferior to the original. Remember, quality photos create questions about the project itself.
Step 4: Attribute Nothing (and Make Sure Nobody Else Does Either)
Pictures are very similar. When stealing pictures, make sure they don't somehow identify the author. If the author is in the picture or otherwise identified, you need to take action. I suggest cropping the identifying portion out of the picture if possible. This doesn't take much work and is an acceptable picture edit, as discussed in the last step. There are other things you could do, but if it's going to be much work, simply steal a different picture. The easy path is the one that pays dividends now, whether it's "right" is for other people to worry about.
Finally, you need to watch your comments in case somebody recognizes that the project is not yours, or even worse that it is theirs. You should immediately flag these comments, and if that fails, you might try threatening the poster's well-being. I'm quite certain a court of law would side with you and allow you to threaten people when they find out the truth.* It's really just up to you to convince them that you're really the one being threatened, as well as being a victim of intellectual property theft.
*This will also be addressed in step five.
Step 5: Lie About Results to Boost Interest
It doesn't matter what the original author tells you about these fun facts. For example, if building your own product would actually cost you more, just say that it would be cheaper. This will attract the attention you are so desperately seeking. Even better yet, make a big flashy and annoying graphic that conveys your idea. After all, if two instructables are otherwise identical, wouldn't you read the one that made the bigger, better claims? Of course you would!
Step 6: Copyright and Claim Ownership
However, if you find something really extraordinary, you should probably use a stronger license to protect your newly-swiped intellect. I was going to steal a link regarding licenses, but the link was broken so I'm just posting a picture of that broken link instead. Remember, it's only stealing if you don't have to work for it!
Step 7: Publish and Answer Comments As If the Ible Was Your Own Unique Idea
Step 8: Hope Original Author Doesn't Notice
Step 9: Go Find Other Ibles to Steal!
You should probably start with stealing less prominent Instructables to build your credibility, and work your way up to the bigger and better ibles after you have more street cred(ability) to back up your claims. Remember, steal from others before they can steal from you! If you have experience stealing other people's instructables, your tips are most welcome. Or, if you've had instructables stolen from you, hopefully you'll be more prepared on how and why this happened so you can avoid such mistakes in the future. This has been instructable number seven, hope you enjoyed it.