Do not use invisible text. This is a modification of keyword stuffing. What the black hatter does is use the same color for both the text and the background for any words they need to hide. While this may make for a better experience for visitors, the search sites see it as cheating and will penalise you for it if you get caught. In this sense we are talking about fake pages that only exist for the purposes of attracting search engine crawlers. There is no target of a living, respiring homo sapien seeing these pages. Again, you will see a short lived increase in your rankings, but could be dropped from the listings completely when the search websites check. It is up to you to read and follow them to the very best of your capability. Once you begin looking for loopholes or excuses, you are moving into black hat SEO territory. So, if that occurs, take that as a sign to do the right thing. Doing the above things will go a ways towards avoiding black hat SEO techniques. This is vital as it will help you to naturally rank higher. You also won’t have to worry about dropping in the rankings if you are caught doing something wrong.