That is to say, if you’re going to start down the road of search engine optimization, you have to know where the potholes are before you get underway. If you’re getting started doing SEO for your blog, here are some of the most important practices to avoid.
- Keyword Stuffing.  Stuffing keywords is only useful  for getting your site penalized or delisted.  Period.  There is no  legitimate reason to do this except to game the search engines, and  they’re very good at detecting it.  Whether you’re putting them in your  content, in alt tags, in meta tags, or wherever, be sure to use your  keywords in moderation.
 - Mirrored Sites and Content Duplication.  “Why  settle for one top 10 rankings when you can have all ten?”  Because it  can cause all of your rankings to drop.  This is the reason that scrapers are dangerous.   Ideally, your content should be as unique as possible to a single  page.  As I mentioned previously, search engines are probably smart  enough to recognize content duplication within blogs (e.g., the same  post text on your home page and the individual post page), so some  duplication isn’t much cause for concern.  Generally speaking, though,  the more unique your content is, the better off you’ll be.
 - Cloaking.  Showing one thing to users and another  thing to search engine spiders is a big red flag.  To those who think  it’s a good idea, here’s a news flash: It’s just as easy for a spider to  change its user agent as it is for a browser.  You can bet search  engine spiders are crawling your site under a variety of names just to  see if you’re cloaking or not, so don’t do it.
 - Hidden Text and Images.  No matter how you hide  content, search engines are smart enough to detect it.  Granted, there  are legitimate reasons to hide content from users, but it’s pretty  obvious when you’re up to something.  Just to be on the safe side,  consider carefully if you really need to hide your content or if you  could find another solution.
 - Cross Linking. Generally speaking, it’s okay to link your sites together. People do it all the time. However, it can be considered spam if you do so excessively (e.g., in the footer or side bar of every page), especially if the sites reside on the same IP block. As with everything else, ask the question, “Is this adding value for the user?” If you can answer yes, it’s probably okay.
 
Knowing and avoiding practices like these is the first step toward ensuring good search engine rankings. Only after realizing what not to do (and correcting it if you’re already doing it) should you move forward with keyword research, content development, link building, and all of the fun parts about SEO. If you are looking for tools that can help you with that, check the SEO Tools compilation that the guys from Search Engine Journal did.