There are many things you should avoid doing, because the Search Engines consider them wrong. Basically, anything that seems to you like you are trying to trick the Search Engines should be avoided. If you go in with the mindset that you want to help the Search Engines understand what your site is about without breaking the Search Engines Terms of Service, then you should be fine.
The fact of the matter is that Search Engines often change what is acceptable and unacceptable in their eyes. Not to mention Search Engines differ on what they believe is wrong vs. right. However, you should try to keep your sites within the general guidelines of most Search Engines.
In the following posts I am going to explain some more things that I believe you should avoid and that most Search Engines say is wrong.
