Google

Google recommends asking the following questions: Can you show me examples of your previous work and share some success stories? Do you follow the Google Webmaster Guidelines? Do you offer any online marketing services to complement your organic search business? What kind of results do you expect to see, and in what time frame? What’s your experience in my industry? How long have you been in business? Beware of black hat practices. Ultimately, you’re responsible for your own site. An unethical SEO might deliver short-term results with very long term consequences, such as getting banned from the search engines for certain shady practices. And once you’re out it’s very difficult to get back in.