| Word of mouth is good. Which comes with time no doubt. But early starters might as well get those 1000s of visitors which may help with word of mouth.
I know most people that I know who run sites have their traffic coming from google almost 90% of the time. I can say that for myself also.
Word of mouth is good, but putting all your eggs in one basket isn't. I don't watch SERPs much but I know what my targets are for visitors and I know google is the one that brings in the most traffic.
I like to keep myself envolved in all 3. |