Hi I have just changed my domain name from a .biz to a .com and now have more keywords in the URL. I used a 301 re-direct. I was led to believe that this was the safest method to preserve rankings. However, a few days after the change my site has lost its good rankings in Google. Has anybody had any experience of this? Is this a temporary thing or do I have to start all over again with SEO for new domain?
A 301 redirect is the best way to go. This should only be a temporary slip or unrelated to the change.
It takes a little time for everything to get sorted out by Google, however you should try out for getting some new inbound links for the new site to get it accelerated.