I want buy now domain from three words: www.my-key-word.com But if it is ok, if I do minuses there? ( " - " ). Or it would be better to buy www.mykeyword.com? Or there is no difference? Please, if you are not sure, do not post answer.
This has been placed into the wrong section of the forum and should have been placed in the Domains area within the Business sector of the site. In relation to your question you should always aim to avoid getting the dashes within a name and more than one dash in your domain name choice will mean that you might as well throw your money down the drain if you are looking to top your search term.
See this comment is what gets people caught out in the world of buying domain names, if you are wanting to rank well within google then the best way is to start with a keyword domain. Domains with more than one dash are SEO suicide unless your search term is low volume.