The shorter your domain name, the easier it will be for people to remember. It also makes it easier to type out, so it's unlikely potential visitors will misspell your address.
Keep it simple
Another important thing is to keep your domain name simple. While it may seem creative to spell 'excellent' as 'xcellent', it can make it confusing for people to remember and type. Avoiding hyphens where possible will also help people remember your domain.
Reflect your business
Avoid going for a domain name that has nothing to do with your business. Make the domain name reflect the contents of your website. if the website is for your business, then your business name should suffice.
Choose the right extension
There are more than 300 domain extensions available, with the most popular being '.com'. While having a domain end in '.com' is desirable, it might not always be the best choice for you. Sometime it is better to use a domain name that ends with your country's extension, such as '.fr'...