What to consider before buy a new domain ? (pls suggest the web sites where I can check the information)
Or if I buy from auction ( what is the safest procedure)
Here is some things to consider when buying or getting a domain from an auction:
How easy will it be for people to remember?
What purpose does the domain represent; a business, organization, from a country (you want to show your association with a country, or a more specialized need like .tv or .info?
How hard will it be to build up traffic to the site, will buying an auctioned domain (that has accurate stats) you may get some traffic from those people/search engines/blogs... that previously indexed the default url of the domain.
Is a name that you want only available via auction?
You should diligently search the web if you choose to buy a domain that there is not well established ill-will towards the domain in the Web community. It is best not to buy an image problem and have to turn it around; better to start fresh.
A Daughter site of sitepoint.com, https://flippa.com/ is a safe place to purchase an auction site. Many people find GoDaddy.com a good place to purchase and manage their domains. Personally I like easydns.com as they have fantastic support and great DNS tools for managing the different public DNS features you might need 'like stealth forwarding' as an example.