There are lots of reasons to use subdomains, what ever your reason is make sure you consider the following issues.

  1. This decision will be with your for a long time – so think it through carefully.
  2. Consider why you need a subdomain – what business problem does it solve.
  3. Search Engine Optimization
    • Use researched keywords that work for your business in the subdomain
    • Don't excessively use keywords in the subdomain
    • Don't connect too many keywords in the subdomain
    • Ask yourself if it looks spammy or professional
  4. Keep the subdomain short as possible
  5. Make sure the subdomain is user friendly
    • You want it to be readable
    • You want it to be click able
    • You want it to be concise (a good test – could it be put on a business card easily)

Subdomain names can have big SEO benefits (the parent site passes reputation to the child), but if you push the boundary too far, you could do more damage then good. So pick wisely, think through the issues, and follow the best practices outlined above.