Avoid having numbers in your domain name. People can get confused about whether the numbers is a digit (3) or a word (three). If you want a number in your domain name because there’s a number in your company name, buy both versions (digit and word) and redirect one to the other. Be especially wary about using the number “0” in a domain name as people may see it as the letter “O.” 

^ Mockapetris, P.V. (November 1987). "Domain names - concepts and facilities" (HTML). IETF Documents. IETF. doi:10.17487/RFC1034. Retrieved 24 July 2017. Relative names are either taken relative to a well known origin, or to a list of domains used as a search list. Relative names appear mostly at the user interface, where their interpretation varies from implementation to implementation, and in master files, where they are relative to a single origin domain name. The most common interpretation uses the root "." as either the single origin or as one of the members of the search list, so a multi-label relative name is often one where the trailing dot has been omitted to save typing.
Contact the owner. Before so much as hinting at a price, simply email to ask whether or not the domain is for sale. If you are known or can clearly be linked to a thriving business, create a generic alternate email address through which to contact them, as your success might be leveraged against you. Be aware, however, that an informal-sounding email address is more likely to be regarded as spam or junk mail.
If your purpose in buying a trademarked term as a domain name is to try to confuse people, you’re opening yourself up to having a complaint filed against you and having to give up the domain name. Even if you’re not trying to create confusion, you’re likely to face some legal challenges by buying trademarked terms in your domain name. To be safe, you can search for U.S. trademarks at www.uspto.gov and make sure no one owns a trademark on the name you are considering.
Even if the term isn’t trademarked, don’t buy domains that are just a variation of another domain name. This means avoiding plurals if the singular is taken (mediatemple.net vs. mediatemples.net), hyphenating a phrase (media-temple.net), or adding “my” or some other preposition (mymediatemple.net). Alternately, you might consider buying these variations yourself and set them up so that if someone types one of the variations, they are redirected to your main site.